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Poe AA, Karawani H, Anderson S. Aging effects on the neural representation and perception of consonant transition cues. Hear Res 2024; 448:109034. [PMID: 38781768 PMCID: PMC11156531 DOI: 10.1016/j.heares.2024.109034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 04/16/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024]
Abstract
Older listeners have difficulty processing temporal cues that are important for word discrimination, and deficient processing may limit their ability to benefit from these cues. Here, we investigated aging effects on perception and neural representation of the consonant transition and the factors that contribute to successful perception. To further understand the neural mechanisms underlying the changes in processing from brainstem to cortex, we also examined the factors that contribute to exaggerated amplitudes in cortex. We enrolled 30 younger normal-hearing and 30 older normal-hearing participants who met the criteria of clinically normal hearing. Perceptual identification functions were obtained for the words BEAT and WHEAT on a 7-step continuum of consonant-transition duration. Auditory brainstem responses (ABRs) were recorded to click stimuli and frequency-following responses (FFRs) and cortical auditory-evoked potentials were recorded to the endpoints of the BEAT-WHEAT continuum. Perceptual performance for identification of BEAT vs. WHEAT did not differ between younger and older listeners. However, both subcortical and cortical measures of neural representation showed age group differences, such that FFR phase locking was lower but cortical amplitudes (P1 and N1) were higher in older compared to younger listeners. ABR Wave I amplitude and FFR phase locking, but not audiometric thresholds, predicted early cortical amplitudes. Phase locking to the transition region and early cortical peak amplitudes (P1) predicted performance on the perceptual identification function. Overall, results suggest that the neural representation of transition durations and cortical overcompensation may contribute to the ability to perceive transition duration contrasts. Cortical overcompensation appears to be a maladaptive response to decreased neural firing/synchrony.
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Affiliation(s)
- Abigail Anne Poe
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, USA
| | - Hanin Karawani
- Department of Communication Sciences and Disorders, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
| | - Samira Anderson
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, USA; Neuroscience and Cognitive Science Program, University of Maryland, College Park, Maryland, USA.
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2
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Fujihira H, Yamagishi S, Furukawa S, Kashino M. Auditory brainstem response to paired clicks as a candidate marker of cochlear synaptopathy in humans. Clin Neurophysiol 2024; 165:44-54. [PMID: 38959535 DOI: 10.1016/j.clinph.2024.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 06/02/2024] [Accepted: 06/08/2024] [Indexed: 07/05/2024]
Abstract
OBJECTIVE This study aimed to evaluate whether auditory brainstem response (ABR) using a paired-click stimulation paradigm could serve as a tool for detecting cochlear synaptopathy (CS). METHODS The ABRs to single-clicks and paired-clicks with various inter-click intervals (ICIs) and scores for word intelligibility in degraded listening conditions were obtained from 57 adults with normal hearing. The wave I peak amplitude and root mean square values for the post-wave I response within a range delayed from the wave I peak (referred to as the RMSpost-w1) were calculated for the single- and second-click responses. RESULTS The wave I peak amplitudes did not correlate with age except for the second-click responses at an ICI of 7 ms, and the word intelligibility scores. However, we found that the RMSpost-w1 values for the second-click responses significantly decreased with increasing age. Moreover, the RMSpost-w1 values for the second-click responses at an ICI of 5 ms correlated significantly with the scores for word intelligibility in degraded listening conditions. CONCLUSIONS The magnitude of the post-wave I response for the second-click response could serve as a tool for detecting CS in humans. SIGNIFICANCE Our findings shed new light on the analytical methods of ABR for quantifying CS.
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Affiliation(s)
- Haruna Fujihira
- NTT Communication Science Laboratories, Atsugi, Kanagawa, Japan; Department of Informatics, Faculty of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Japan.
| | | | - Shigeto Furukawa
- NTT Communication Science Laboratories, Atsugi, Kanagawa, Japan; Graduate School of Public Health, Shizuoka Graduate University of Public Health, Shizuoka, Japan; Speech-Language-Hearing Center, Shizuoka General Hospital, Shizuoka, Japan
| | - Makio Kashino
- NTT Communication Science Laboratories, Atsugi, Kanagawa, Japan
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3
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Andéol G, Paraouty N, Giraudet F, Wallaert N, Isnard V, Moulin A, Suied C. Predictors of Speech-in-Noise Understanding in a Population of Occupationally Noise-Exposed Individuals. BIOLOGY 2024; 13:416. [PMID: 38927296 PMCID: PMC11200776 DOI: 10.3390/biology13060416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/20/2024] [Accepted: 05/21/2024] [Indexed: 06/28/2024]
Abstract
Understanding speech in noise is particularly difficult for individuals occupationally exposed to noise due to a mix of noise-induced auditory lesions and the energetic masking of speech signals. For years, the monitoring of conventional audiometric thresholds has been the usual method to check and preserve auditory function. Recently, suprathreshold deficits, notably, difficulties in understanding speech in noise, has pointed out the need for new monitoring tools. The present study aims to identify the most important variables that predict speech in noise understanding in order to suggest a new method of hearing status monitoring. Physiological (distortion products of otoacoustic emissions, electrocochleography) and behavioral (amplitude and frequency modulation detection thresholds, conventional and extended high-frequency audiometric thresholds) variables were collected in a population of individuals presenting a relatively homogeneous occupational noise exposure. Those variables were used as predictors in a statistical model (random forest) to predict the scores of three different speech-in-noise tests and a self-report of speech-in-noise ability. The extended high-frequency threshold appears to be the best predictor and therefore an interesting candidate for a new way of monitoring noise-exposed professionals.
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Affiliation(s)
- Guillaume Andéol
- Institut de Recherche Biomédicale des Armées, 1 Place Valérie André, 91220 Brétigny sur Orge, France; (V.I.); (C.S.)
| | - Nihaad Paraouty
- iAudiogram—My Medical Assistant SAS, 51100 Reims, France; (N.P.); (N.W.)
| | - Fabrice Giraudet
- Department of Neurosensory Biophysics, INSERM U1107 NEURO-DOL, School of Medecine, Université Clermont Auvergne, 63000 Clermont-Ferrand, France;
| | - Nicolas Wallaert
- iAudiogram—My Medical Assistant SAS, 51100 Reims, France; (N.P.); (N.W.)
- Laboratoire des Systèmes Perceptifs, UMR CNRS 8248, Département d’Etudes Cognitives, Ecole Normale Supérieure, Université Paris Sciences et Lettres (PSL), 75005 Paris, France
- Department of Otorhinolaryngology-Head and Neck Surgery, Rennes University Hospital, 35000 Rennes, France
| | - Vincent Isnard
- Institut de Recherche Biomédicale des Armées, 1 Place Valérie André, 91220 Brétigny sur Orge, France; (V.I.); (C.S.)
| | - Annie Moulin
- Centre de Recherche en Neurosciences de Lyon, CRNL Inserm U1028—CNRS UMR5292—UCBLyon1, Perception Attention Memory Team, Bâtiment 452 B, 95 Bd Pinel, 69675 Bron Cedex, France;
| | - Clara Suied
- Institut de Recherche Biomédicale des Armées, 1 Place Valérie André, 91220 Brétigny sur Orge, France; (V.I.); (C.S.)
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4
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Dias JW, McClaskey CM, Alvey AP, Lawson A, Matthews LJ, Dubno JR, Harris KC. Effects of age and noise exposure history on auditory nerve response amplitudes: A systematic review, study, and meta-analysis. Hear Res 2024; 447:109010. [PMID: 38744019 PMCID: PMC11135078 DOI: 10.1016/j.heares.2024.109010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/08/2024] [Accepted: 04/18/2024] [Indexed: 05/16/2024]
Abstract
Auditory nerve (AN) function has been hypothesized to deteriorate with age and noise exposure. Here, we perform a systematic review of published studies and find that the evidence for age-related deficits in AN function is largely consistent across the literature, but there are inconsistent findings among studies of noise exposure history. Further, evidence from animal studies suggests that the greatest deficits in AN response amplitudes are found in noise-exposed aged mice, but a test of the interaction between effects of age and noise exposure on AN function has not been conducted in humans. We report a study of our own examining differences in the response amplitude of the compound action potential N1 (CAP N1) between younger and older adults with and without a self-reported history of noise exposure in a large sample of human participants (63 younger adults 18-30 years of age, 103 older adults 50-86 years of age). CAP N1 response amplitudes were smaller in older than younger adults. Noise exposure history did not appear to predict CAP N1 response amplitudes, nor did the effect of noise exposure history interact with age. We then incorporated our results into two meta-analyses of published studies of age and noise exposure history effects on AN response amplitudes in neurotypical human samples. The meta-analyses found that age effects across studies are robust (r = -0.407), but noise exposure effects are weak (r = -0.152). We conclude that noise exposure effects may be highly variable depending on sample characteristics, study design, and statistical approach, and researchers should be cautious when interpreting results. The underlying pathology of age-related and noise-induced changes in AN function are difficult to determine in living humans, creating a need for longitudinal studies of changes in AN function across the lifespan and histological examination of the AN from temporal bones collected post-mortem.
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Affiliation(s)
- James W Dias
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States.
| | - Carolyn M McClaskey
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - April P Alvey
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Abigail Lawson
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Lois J Matthews
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Judy R Dubno
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
| | - Kelly C Harris
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, SC 29425-5500, United States
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Schmidt FH, Dörmann A, Ehrt K, Grossmann W, Mlynski R, Zhang L. The curvature quantification of wave I in auditory brainstem responses detects cochlear synaptopathy in human beings. Eur Arch Otorhinolaryngol 2024:10.1007/s00405-024-08699-6. [PMID: 38703194 DOI: 10.1007/s00405-024-08699-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 04/18/2024] [Indexed: 05/06/2024]
Abstract
PURPOSE Patients with age-related hearing loss complain often about reduced speech perception in adverse listening environment. Studies on animals have suggested that cochlear synaptopathy may be one of the primary mechanisms responsible for this phenomenon. A decreased wave I amplitude in supra-threshold auditory brainstem response (ABR) can diagnose this pathology non-invasively. However, the interpretation of the wave I amplitude in humans remains controversial. Recent studies in mice have established a robust and reliable mathematic algorithm, i.e., curve curvature quantification, for detecting cochlear synaptopathy. This study aimed to determine whether the curve curvature has sufficient test-retest reliability to detect cochlear synaptopathy in aging humans. METHODS Healthy participants were recruited into this prospective study. All subjects underwent an audiogram examination with standard and extended high frequencies ranging from 0.125 to 16 kHz and an ABR with a stimulus of 80 dB nHL click. The peak amplitude, peak latency, curvature at the peak, and the area under the curve of wave I were calculated and analyzed. RESULTS A total of 80 individuals with normal hearing, aged 18 to 61 years, participated in this study, with a mean age of 26.4 years. Pearson correlation analysis showed a significant negative correlation between curvature and age, as well as between curvature and extended high frequency (EHF) threshold (10-16 kHz). Additionally, the same correlation was observed between age and area as well as age and EHF threshold. The model comparison demonstrated that the curvature at the peak of wave I is the best metric to correlate with EHF threshold. CONCLUSION The curvature at the peak of wave I is the most sensitive metric for detecting cochlear synaptopathy in humans and may be applied in routine diagnostics to detect early degenerations of the auditory nerve.
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Affiliation(s)
- Florian Herrmann Schmidt
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto Körner, Rostock University Medical Center, Doberaner Strasse 137-139, 18057, Rostock, Germany
| | - Alexander Dörmann
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto Körner, Rostock University Medical Center, Doberaner Strasse 137-139, 18057, Rostock, Germany
| | - Karsten Ehrt
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto Körner, Rostock University Medical Center, Doberaner Strasse 137-139, 18057, Rostock, Germany
| | - Wilma Grossmann
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto Körner, Rostock University Medical Center, Doberaner Strasse 137-139, 18057, Rostock, Germany
| | - Robert Mlynski
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto Körner, Rostock University Medical Center, Doberaner Strasse 137-139, 18057, Rostock, Germany
| | - Lichun Zhang
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto Körner, Rostock University Medical Center, Doberaner Strasse 137-139, 18057, Rostock, Germany.
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Temboury-Gutierrez M, Märcher-Rørsted J, Bille M, Yde J, Encina-Llamas G, Hjortkjær J, Dau T. Electrocochleographic frequency-following responses as a potential marker of age-related cochlear neural degeneration. Hear Res 2024; 446:109005. [PMID: 38598943 DOI: 10.1016/j.heares.2024.109005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 03/19/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024]
Abstract
Auditory nerve (AN) fibers that innervate inner hair cells in the cochlea degenerate with advancing age. It has been proposed that age-related reductions in brainstem frequency-following responses (FFR) to the carrier of low-frequency, high-intensity pure tones may partially reflect this neural loss in the cochlea (Märcher-Rørsted et al., 2022). If the loss of AN fibers is the primary factor contributing to age-related changes in the brainstem FFR, then the FFR could serve as an indicator of cochlear neural degeneration. In this study, we employed electrocochleography (ECochG) to investigate the effects of age on frequency-following neurophonic potentials, i.e., neural responses phase-locked to the carrier frequency of the tone stimulus. We compared these findings to the brainstem-generated FFRs obtained simultaneously using the same stimulation. We conducted recordings in young and older individuals with normal hearing. Responses to pure tones (250 ms, 516 and 1086 Hz, 85 dB SPL) and clicks were recorded using both ECochG at the tympanic membrane and traditional scalp electroencephalographic (EEG) recordings of the FFR. Distortion product otoacoustic emissions (DPOAE) were also collected. In the ECochG recordings, sustained AN neurophonic (ANN) responses to tonal stimulation, as well as the click-evoked compound action potential (CAP) of the AN, were significantly reduced in the older listeners compared to young controls, despite normal audiometric thresholds. In the EEG recordings, brainstem FFRs to the same tone stimulation were also diminished in the older participants. Unlike the reduced AN CAP response, the transient-evoked wave-V remained unaffected. These findings could indicate that a decreased number of AN fibers contributes to the response in the older participants. The results suggest that the scalp-recorded FFR, as opposed to the clinical standard wave-V of the auditory brainstem response, may serve as a more reliable indicator of age-related cochlear neural degeneration.
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Affiliation(s)
- Miguel Temboury-Gutierrez
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark.
| | - Jonatan Märcher-Rørsted
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark
| | - Michael Bille
- Copenhagen Hearing and Balance Center, Ear, Nose and Throat (ENT) and Audiology Clinic, Rigshospitalet, Copenhagen University Hospital, Denmark, Inge Lehmanns Vej 8, DK-2100 København Ø, Denmark
| | - Jesper Yde
- Copenhagen Hearing and Balance Center, Ear, Nose and Throat (ENT) and Audiology Clinic, Rigshospitalet, Copenhagen University Hospital, Denmark, Inge Lehmanns Vej 8, DK-2100 København Ø, Denmark
| | - Gerard Encina-Llamas
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark; Copenhagen Hearing and Balance Center, Ear, Nose and Throat (ENT) and Audiology Clinic, Rigshospitalet, Copenhagen University Hospital, Denmark, Inge Lehmanns Vej 8, DK-2100 København Ø, Denmark; Faculty of Medicine. University of Vic - Central University of Catalonia (UVic-UCC), Vic, 08500, Catalonia - Spain
| | - Jens Hjortkjær
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark; Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Kettegård Allé 30, DK-2650 Hvidovre, Denmark
| | - Torsten Dau
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Ørsteds Plads, Building 352, DK-2800 Kgs. Lyngby, Denmark
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Dias JW, McClaskey CM, Alvey AP, Lawson A, Matthews LJ, Dubno JR, Harris KC. Effects of Age and Noise Exposure History on Auditory Nerve Response Amplitudes: A Systematic Review, Study, and Meta-Analysis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.20.585882. [PMID: 38585917 PMCID: PMC10996537 DOI: 10.1101/2024.03.20.585882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Auditory nerve (AN) function has been hypothesized to deteriorate with age and noise exposure. Here, we perform a systematic review of published studies and find that the evidence for age-related deficits in AN function is largely consistent across the literature, but there are inconsistent findings among studies of noise exposure history. Further, evidence from animal studies suggests that the greatest deficits in AN response amplitudes are found in noise-exposed aged mice, but a test of the interaction between effects of age and noise exposure on AN function has not been conducted in humans. We report a study of our own examining differences in the response amplitude of the compound action potential N1 (CAP N1) between younger and older adults with and without a self-reported history of noise exposure in a large sample of human participants (63 younger adults 18-30 years of age, 103 older adults 50-86 years of age). CAP N1 response amplitudes were smaller in older than younger adults. Noise exposure history did not appear to predict CAP N1 response amplitudes, nor did the effect of noise exposure history interact with age. We then incorporated our results into two meta-analyses of published studies of age and noise exposure history effects on AN response amplitudes in neurotypical human samples. The meta-analyses found that age effects across studies are robust (r=-0.407), but noise-exposure effects are weak (r=-0.152). We conclude that noise-exposure effects may be highly variable depending on sample characteristics, study design, and statistical approach, and researchers should be cautious when interpreting results. The underlying pathology of age-related and noise-induced changes in AN function are difficult to determine in living humans, creating a need for longitudinal studies of changes in AN function across the lifespan and histological examination of the AN from temporal bones collected post-mortem.
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Affiliation(s)
- James W Dias
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Carolyn M McClaskey
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - April P Alvey
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Abigail Lawson
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Lois J Matthews
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Judy R Dubno
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
| | - Kelly C Harris
- Medical University of South Carolina Department of Otolaryngology - Head and Neck Surgery
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Patro C, Monfiletto A, Singer A, Srinivasan NK, Mishra SK. Midlife Speech Perception Deficits: Impact of Extended High-Frequency Hearing, Peripheral Neural Function, and Cognitive Abilities. Ear Hear 2024:00003446-990000000-00269. [PMID: 38556645 DOI: 10.1097/aud.0000000000001504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
OBJECTIVES The objectives of the present study were to investigate the effects of age-related changes in extended high-frequency (EHF) hearing, peripheral neural function, working memory, and executive function on speech perception deficits in middle-aged individuals with clinically normal hearing. DESIGN We administered a comprehensive assessment battery to 37 participants spanning the age range of 20 to 56 years. This battery encompassed various evaluations, including standard and EHF pure-tone audiometry, ranging from 0.25 to 16 kHz. In addition, we conducted auditory brainstem response assessments with varying stimulation rates and levels, a spatial release from masking (SRM) task, and cognitive evaluations that involved the Trail Making test (TMT) for assessing executive function and the Abbreviated Reading Span test (ARST) for measuring working memory. RESULTS The results indicated a decline in hearing sensitivities at EHFs and an increase in completion times for the TMT with age. In addition, as age increased, there was a corresponding decrease in the amount of SRM. The declines in SRM were associated with age-related declines in hearing sensitivity at EHFs and TMT performance. While we observed an age-related decline in wave I responses, this decline was primarily driven by age-related reductions in EHF thresholds. In addition, the results obtained using the ARST did not show an age-related decline. Neither the auditory brainstem response results nor ARST scores were correlated with the amount of SRM. CONCLUSIONS These findings suggest that speech perception deficits in middle age are primarily linked to declines in EHF hearing and executive function, rather than cochlear synaptopathy or working memory.
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Affiliation(s)
- Chhayakanta Patro
- Department of Speech Language Pathology & Audiology, Towson University, Towson, Maryland, USA
| | - Angela Monfiletto
- Department of Speech Language Pathology & Audiology, Towson University, Towson, Maryland, USA
| | - Aviya Singer
- Department of Speech Language Pathology & Audiology, Towson University, Towson, Maryland, USA
| | - Nirmal Kumar Srinivasan
- Department of Speech Language Pathology & Audiology, Towson University, Towson, Maryland, USA
| | - Srikanta Kumar Mishra
- Department of Speech, Language and Hearing Sciences, The University of Texas at Austin, Austin, Texas, USA
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9
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Maass JC, Leiva A, Torrente M, Vergara R, Belkhiria C, Delgado C, Delano PH. Supra-Threshold LS CE-Chirp Auditory Brainstem Response in the Elderly. Audiol Neurootol 2024:1-10. [PMID: 38437806 DOI: 10.1159/000533683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 08/16/2023] [Indexed: 03/06/2024] Open
Abstract
INTRODUCTION Aging deteriorates peripheral and central auditory structures and functions. In elders, for an accurate audiological evaluation, it is important to explore beyond the cochlear receptor. Audiograms provide an estimation of hearing thresholds, while the amplitudes and latencies of supra-threshold auditory brainstem response (ABR) can offer noninvasive measures of the auditory pathways functioning. Regarding ABR, in young populations, level-specific chirp (LS CE-chirp) stimulus has been proposed as an alternative synchronizing method to obtain larger ABR responses than those evoked by clicks. However, the supra-threshold characteristics of chirp evoked ABR, and their association to hearing thresholds is relatively unknown in the elderly. The aim of this study was to evaluate supra-threshold LS CE-chirp ABRs in an aged population by comparing their features with click ABRs, and evaluating their relationship with audiometric hearing thresholds. METHODS We carried out a cross-sectional study to characterize the hearing of 125 adults aged over 65 years. We determined the audiometric hearing thresholds and supra-threshold ABRs elicited by LS CE-chirp and click stimuli at 80 dB nHL. We evaluated associations by means of partial correlations and covariate adjustment. We performed specific frequencies' analysis and subgroup analysis per hearing level. RESULTS Wave V responses had significantly shorter latencies and larger amplitudes when elicited by LS CE-chirp as compared to click-evoked responses. Audiometric hearing thresholds correlated with age, but ABR characteristics did not. We found mild correlations between hearing thresholds and ABR characteristics, predominantly at higher frequencies and with chirp. We found scarce evidence of correlation between ABR characteristics and the average of behavioral hearing thresholds between 0.5 to 4 kHz (0.5-4 kHz PTA). After subgroup analysis according to the hearing level, no stronger or more significant correlations were found between ABR characteristics and 0.5-4 kHz PTA. DISCUSSION In this study, we found that supra-threshold LS CE-chirp ABR presented some of the previously described similitudes and differences with supra-threshold click ABR in younger populations. Although, the average amplitude and latency of wave V evoked by LS CE-chirp were larger and faster than those evoked by clicks, these results should be taken with caution at the individual level, and further studies are required to state that LS CE-chirp ABRs are better than click ABRs in elders for clinical evaluations. We did not find consistent associations between hearing thresholds and supra-threshold wave V features, suggesting that these measures should be considered independently in the elderly.
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Affiliation(s)
- Juan C Maass
- Interdisciplinary Program of Physiology and Biophysics, Instituto de Ciencias Biomédicas, Facultad de Medicina Universidad de Chile, Santiago, Chile,
- Otolaryngology Department, Hospital Clínico Universidad de Chile, Santiago, Chile,
| | - Alexis Leiva
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Biomedical Neuroscience Institute, BNI, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Mariela Torrente
- Otolaryngology Department, Hospital Clínico Universidad de Chile, Santiago, Chile
| | - Rodrigo Vergara
- Facultad de Psicología y Humanidades, Universidad San Sebastián, Valdivia, Chile
- Centro Nacional de Inteligencia Artificial CENIA, Santiago, Chile
| | - Chama Belkhiria
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Biomedical Neuroscience Institute, BNI, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Carolina Delgado
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Neurology and Neurosurgery Department, Hospital Clínico Universidad de Chile, Santiago, Chile
| | - Paul H Delano
- Otolaryngology Department, Hospital Clínico Universidad de Chile, Santiago, Chile
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Biomedical Neuroscience Institute, BNI, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Centro Avanzado de Ingeniería Eléctrica y Electrónica, AC3E, Universidad Técnica Federico Santa María, Valparaíso, Chile
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10
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Liu J, Stohl J, Overath T. Hidden hearing loss: Fifteen years at a glance. Hear Res 2024; 443:108967. [PMID: 38335624 DOI: 10.1016/j.heares.2024.108967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 01/15/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024]
Abstract
Hearing loss affects approximately 18% of the population worldwide. Hearing difficulties in noisy environments without accompanying audiometric threshold shifts likely affect an even larger percentage of the global population. One of the potential causes of hidden hearing loss is cochlear synaptopathy, the loss of synapses between inner hair cells (IHC) and auditory nerve fibers (ANF). These synapses are the most vulnerable structures in the cochlea to noise exposure or aging. The loss of synapses causes auditory deafferentation, i.e., the loss of auditory afferent information, whose downstream effect is the loss of information that is sent to higher-order auditory processing stages. Understanding the physiological and perceptual effects of this early auditory deafferentation might inform interventions to prevent later, more severe hearing loss. In the past decade, a large body of work has been devoted to better understand hidden hearing loss, including the causes of hidden hearing loss, their corresponding impact on the auditory pathway, and the use of auditory physiological measures for clinical diagnosis of auditory deafferentation. This review synthesizes the findings from studies in humans and animals to answer some of the key questions in the field, and it points to gaps in knowledge that warrant more investigation. Specifically, recent studies suggest that some electrophysiological measures have the potential to function as indicators of hidden hearing loss in humans, but more research is needed for these measures to be included as part of a clinical test battery.
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Affiliation(s)
- Jiayue Liu
- Department of Psychology and Neuroscience, Duke University, Durham, USA.
| | - Joshua Stohl
- North American Research Laboratory, MED-EL Corporation, Durham, USA
| | - Tobias Overath
- Department of Psychology and Neuroscience, Duke University, Durham, USA
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Henry KS, Guo AA, Abrams KS. Normal behavioral discrimination of envelope statistics in budgerigars with kainate-induced cochlear synaptopathy. Hear Res 2024; 441:108927. [PMID: 38096707 PMCID: PMC10775186 DOI: 10.1016/j.heares.2023.108927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/27/2023] [Accepted: 12/04/2023] [Indexed: 12/27/2023]
Abstract
Cochlear synaptopathy is a common pathology in humans associated with aging and potentially sound overexposure. Synaptopathy is widely expected to cause "hidden hearing loss," including difficulty perceiving speech in noise, but support for this hypothesis is controversial. Here in budgerigars (Melopsittacus undulatus), we evaluated the impact of long-term cochlear synaptopathy on behavioral discrimination of Gaussian noise (GN) and low-noise noise (LNN) signals processed to have a flatter envelope. Stimuli had center frequencies of 1-3kHz, 100-Hz bandwidth, and were presented at sensation levels (SLs) from 10 to 30dB. We reasoned that narrowband, low-SL stimuli of this type should minimize spread of excitation across auditory-nerve fibers, and hence might reveal synaptopathy-related defects if they exist. Cochlear synaptopathy was induced without hair-cell injury using kainic acid (KA). Behavioral threshold tracking experiments characterized the minimum stimulus duration above which animals could reliably discriminate between LNN and GN. Budgerigar thresholds for LNN-GN discrimination ranged from 40 to 60ms at 30dB SL, were similar across frequencies, and increased for lower SLs. Notably, animals with long-term 39-77% estimated synaptopathy performed similarly to controls, requiring on average a ∼7.5% shorter stimulus duration (-0.7±1.0dB; mean difference ±SE) for LNN-GN discrimination. Decision-variable correlation analyses of detailed behavioral response patterns showed that individual animals relied on envelope cues to discriminate LNN and GN, with lesser roles of FM and energy cues; no difference was found between KA-exposed and control groups. These results suggest that long-term cochlear synaptopathy does not impair discrimination of low-level signals with different envelope statistics.
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Affiliation(s)
- Kenneth S Henry
- Department of Otolaryngology, University of Rochester, NY 14642, USA; Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA; Department of Neuroscience, University of Rochester, Rochester, NY 14642, USA.
| | - Anna A Guo
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14642, USA
| | - Kristina S Abrams
- Department of Neuroscience, University of Rochester, Rochester, NY 14642, USA
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Liu J, Stohl J, Lopez-Poveda EA, Overath T. Quantifying the Impact of Auditory Deafferentation on Speech Perception. Trends Hear 2024; 28:23312165241227818. [PMID: 38291713 PMCID: PMC10832414 DOI: 10.1177/23312165241227818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 12/22/2023] [Accepted: 01/05/2024] [Indexed: 02/01/2024] Open
Abstract
The past decade has seen a wealth of research dedicated to determining which and how morphological changes in the auditory periphery contribute to people experiencing hearing difficulties in noise despite having clinically normal audiometric thresholds in quiet. Evidence from animal studies suggests that cochlear synaptopathy in the inner ear might lead to auditory nerve deafferentation, resulting in impoverished signal transmission to the brain. Here, we quantify the likely perceptual consequences of auditory deafferentation in humans via a physiologically inspired encoding-decoding model. The encoding stage simulates the processing of an acoustic input stimulus (e.g., speech) at the auditory periphery, while the decoding stage is trained to optimally regenerate the input stimulus from the simulated auditory nerve firing data. This allowed us to quantify the effect of different degrees of auditory deafferentation by measuring the extent to which the decoded signal supported the identification of speech in quiet and in noise. In a series of experiments, speech perception thresholds in quiet and in noise increased (worsened) significantly as a function of the degree of auditory deafferentation for modeled deafferentation greater than 90%. Importantly, this effect was significantly stronger in a noisy than in a quiet background. The encoding-decoding model thus captured the hallmark symptom of degraded speech perception in noise together with normal speech perception in quiet. As such, the model might function as a quantitative guide to evaluating the degree of auditory deafferentation in human listeners.
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Affiliation(s)
- Jiayue Liu
- Department of Psychology and Neuroscience, Duke University, Durham, NC, USA
| | - Joshua Stohl
- North American Research Laboratory, MED-EL Corporation, Durham, NC, USA
| | - Enrique A. Lopez-Poveda
- Instituto de Neurociencias de Castilla y Leon, University of Salamanca, Salamanca, Spain
- Departamento de Cirugía, Facultad de Medicina, University of Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Tobias Overath
- Department of Psychology and Neuroscience, Duke University, Durham, NC, USA
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Bramhall NF, McMillan GP. Perceptual Consequences of Cochlear Deafferentation in Humans. Trends Hear 2024; 28:23312165241239541. [PMID: 38738337 DOI: 10.1177/23312165241239541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024] Open
Abstract
Cochlear synaptopathy, a form of cochlear deafferentation, has been demonstrated in a number of animal species, including non-human primates. Both age and noise exposure contribute to synaptopathy in animal models, indicating that it may be a common type of auditory dysfunction in humans. Temporal bone and auditory physiological data suggest that age and occupational/military noise exposure also lead to synaptopathy in humans. The predicted perceptual consequences of synaptopathy include tinnitus, hyperacusis, and difficulty with speech-in-noise perception. However, confirming the perceptual impacts of this form of cochlear deafferentation presents a particular challenge because synaptopathy can only be confirmed through post-mortem temporal bone analysis and auditory perception is difficult to evaluate in animals. Animal data suggest that deafferentation leads to increased central gain, signs of tinnitus and abnormal loudness perception, and deficits in temporal processing and signal-in-noise detection. If equivalent changes occur in humans following deafferentation, this would be expected to increase the likelihood of developing tinnitus, hyperacusis, and difficulty with speech-in-noise perception. Physiological data from humans is consistent with the hypothesis that deafferentation is associated with increased central gain and a greater likelihood of tinnitus perception, while human data on the relationship between deafferentation and hyperacusis is extremely limited. Many human studies have investigated the relationship between physiological correlates of deafferentation and difficulty with speech-in-noise perception, with mixed findings. A non-linear relationship between deafferentation and speech perception may have contributed to the mixed results. When differences in sample characteristics and study measurements are considered, the findings may be more consistent.
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Affiliation(s)
- Naomi F Bramhall
- VA National Center for Rehabilitative Auditory Research, Veterans Affairs Portland Health Care System, Portland, OR, USA
- Department of Otolaryngology/Head & Neck Surgery, Oregon Health & Science University, Portland, OR, USA
| | - Garnett P McMillan
- VA National Center for Rehabilitative Auditory Research, Veterans Affairs Portland Health Care System, Portland, OR, USA
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Vasilkov V, Caswell-Midwinter B, Zhao Y, de Gruttola V, Jung DH, Liberman MC, Maison SF. Evidence of cochlear neural degeneration in normal-hearing subjects with tinnitus. Sci Rep 2023; 13:19870. [PMID: 38036538 PMCID: PMC10689483 DOI: 10.1038/s41598-023-46741-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 11/04/2023] [Indexed: 12/02/2023] Open
Abstract
Tinnitus, reduced sound-level tolerance, and difficulties hearing in noisy environments are the most common complaints associated with sensorineural hearing loss in adult populations. This study aims to clarify if cochlear neural degeneration estimated in a large pool of participants with normal audiograms is associated with self-report of tinnitus using a test battery probing the different stages of the auditory processing from hair cell responses to the auditory reflexes of the brainstem. Self-report of chronic tinnitus was significantly associated with (1) reduced cochlear nerve responses, (2) weaker middle-ear muscle reflexes, (3) stronger medial olivocochlear efferent reflexes and (4) hyperactivity in the central auditory pathways. These results support the model of tinnitus generation whereby decreased neural activity from a damaged cochlea can elicit hyperactivity from decreased inhibition in the central nervous system.
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Affiliation(s)
- Viacheslav Vasilkov
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA, 02114, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA
| | - Benjamin Caswell-Midwinter
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA, 02114, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA
| | - Yan Zhao
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA, 02114, USA
| | - Victor de Gruttola
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, 02114, USA
| | - David H Jung
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA, 02114, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA, 02114, USA
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA
| | - Stéphane F Maison
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA, 02114, USA.
- Department of Otolaryngology, Harvard Medical School, Boston, MA, 02114, USA.
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Colla MDF, Lunardelo PP, Dias FAM. Cochlear synaptopathy and hidden hearing loss: a scoping review. Codas 2023; 36:e20230032. [PMID: 37991055 DOI: 10.1590/2317-1782/20232023032pt] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 07/10/2023] [Indexed: 11/23/2023] Open
Abstract
PURPOSE To identify the pathophysiological definitions adopted by studies investigating "cochlear synaptopathy" (CS) and "hidden hearing loss" (HHL). RESEARCH STRATEGIES The combination of keywords "Auditory Synaptopathy" or "Neuronal Synaptopathy" or "Hidden Hearing Loss" with "etiology" or "causality" or "diagnosis" was used in the databases EMBASE, Pubmed (MEDLINE), CINAHL (EBSCO), and Web of Science. SELECTION CRITERIA Studies that investigated CS or HHL in humans using behavioral and/or electrophysiological procedures were included. DATA ANALYSIS Data analysis and extraction were performed with regard to terminology, definitions, and population. RESULTS 49 articles were included. Of these, 61.2% used the CS terminology, 34.7% used both terms, and 4.1% used HHL. The most-studied conditions were exposure to noise and tinnitus. CONCLUSION CS terminology was used in most studies, referring to the pathophysiological process of deafferentiation between the cochlear nerve fibers and inner hair cells.
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Affiliation(s)
- Marina de Figueiredo Colla
- Departamento de Fonoaudiologia, Pontifícia Universidade Católica de Minas Gerais - PUC MG - Belo Horizonte (MG), Brasil
| | - Pamela Papile Lunardelo
- Programa de Pós-graduação em Psicobiologia, Universidade de São Paulo de Ribeirão Preto - USP RP - Ribeirão Preto (SP), Brasil
| | - Fernanda Abalen Martins Dias
- Departamento de Fonoaudiologia, Pontifícia Universidade Católica de Minas Gerais - PUC MG - Belo Horizonte (MG), Brasil
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Morse K, Vander Werff K. The Effect of Tinnitus and Related Characteristics on Subcortical Auditory Processing. Ear Hear 2023; 44:1344-1353. [PMID: 37127904 DOI: 10.1097/aud.0000000000001376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
OBJECTIVES The primary aim of this study was to evaluate whether individuals with tinnitus exhibited evidence of reduced inhibition and increased excitation at the subcortical auditory processing level. Based on the proposed mechanism of tinnitus generation, including peripheral auditory insult that triggers reduced inhibition and subcortical hyperactivity, it was hypothesized that a tinnitus group would yield reduced amplitudes for the most peripheral auditory brainstem response (ABR) component (wave I) and larger amplitudes for the most central ABR component (wave V) relative to controls matched on factors of age, sex, and hearing loss. Further, this study assessed the relative influence of tinnitus presence versus other related individual characteristics, including hearing loss, age, noise exposure history, and speech perception in noise on these ABR outcomes. DESIGN Subcortical processing was examined using click-evoked ABR in an independent groups experimental design. A group of adults who perceived daily unilateral or bilateral tinnitus were matched with a control group counterpart without tinnitus by age, hearing, and sex (in each group n = 18; 10 females, 8 males). Amplitudes for ABR waves I, III, V, and the V/I ratio were compared between groups by independent t-tests. The relative influence of tinnitus (presence/absence), age (in years), noise exposure history (subjective self-report), hearing loss (audiometric thresholds), and speech perception in noise (SNR-50) was determined based on the proportional reduction in error associated with accounting for each variable of interest using multiple regression. RESULTS Between-group trends were consistent with smaller amplitudes for all ABR components in individuals with tinnitus. Contrary to our hypotheses, however, none of the tinnitus compared with control group differences in ABR outcomes were statistically significant. In the multiple regression models, none of the factors including tinnitus presence, age, noise exposure history, hearing loss, and speech perception in noise significantly predicted ABR V/I ratio outcomes. CONCLUSIONS The presence of reduced inhibition and subcortical hyperactivity in the tinnitus group was not supported in the current study. There were trends in ABR outcomes consistent with reduced peripheral to central brainstem auditory activity in the tinnitus group, but none of the group differences reached significance. It should also be noted that the tinnitus group had poorer extended high-frequency thresholds compared with controls. Regardless, neither tinnitus presence nor any of the proposed related characteristics were found to significantly influence the ABR V/I ratio. These findings suggest that either reduced subcortical inhibition was not a primary underlying mechanism for the tinnitus perceived by these subjects, or that ABR was not a reliable indicator of reduced subcortical inhibition possibly due to characteristics of the sample including a skewed distributions toward young and normal hearing individuals with little tinnitus distress.
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Affiliation(s)
- Kenneth Morse
- Division of Communication Sciences and Disorders, West Virginia University, Morgantown, West Virginia, USA
| | - Kathy Vander Werff
- Department of Communication Sciences and Disorders, Syracuse University, Syracuse, New York, USA
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Shehabi AM, Prendergast G, Guest H, Plack CJ. Noise Exposure in Palestinian Workers Without a Diagnosis of Hearing Impairment: Relations to Speech-Perception-in-Noise Difficulties, Tinnitus, and Hyperacusis. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2023; 66:1085-1109. [PMID: 36802819 DOI: 10.1044/2022_jslhr-22-00461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
PURPOSE Many workers in developing countries are exposed to unsafe occupational noise due to inadequate health and safety practices. We tested the hypotheses that occupational noise exposure and aging affect speech-perception-in-noise (SPiN) thresholds, self-reported hearing ability, tinnitus presence, and hyperacusis severity among Palestinian workers. METHOD Palestinian workers (N = 251, aged 18-70 years) without diagnosed hearing or memory impairments completed online instruments including a noise exposure questionnaire; forward and backward digit span tests; hyperacusis questionnaire; the short-form Speech, Spatial and Qualities of Hearing Scale (SSQ12); the Tinnitus Handicap Inventory; and a digits-in-noise (DIN) test. Hypotheses were tested via multiple linear and logistic regression models, including age and occupational noise exposure as predictors, and with sex, recreational noise exposure, cognitive ability, and academic attainment as covariates. Familywise error rate was controlled across all 16 comparisons using the Bonferroni-Holm method. Exploratory analyses evaluated effects on tinnitus handicap. A comprehensive study protocol was preregistered. RESULTS Nonsignificant trends of poorer SPiN performance, poorer self-reported hearing ability, greater prevalence of tinnitus, greater tinnitus handicap, and greater severity of hyperacusis as a function of higher occupational noise exposure were observed. Greater hyperacusis severity was significantly predicted by higher occupational noise exposure. Aging was significantly associated with higher DIN thresholds and lower SSQ12 scores, but not with tinnitus presence, tinnitus handicap, or hyperacusis severity. CONCLUSIONS Workers in Palestine may suffer from auditory effects of occupational noise and aging despite no formal diagnosis. These findings highlight the importance of occupational noise monitoring and hearing-related health and safety practices in developing countries. SUPPLEMENTAL MATERIAL https://doi.org/10.23641/asha.22056701.
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Affiliation(s)
- Adnan M Shehabi
- Manchester Centre for Audiology and Deafness, The University of Manchester, United Kingdom
- Department of Audiology and Speech Therapy, Birzeit University, Palestine
| | - Garreth Prendergast
- Manchester Centre for Audiology and Deafness, The University of Manchester, United Kingdom
| | - Hannah Guest
- Manchester Centre for Audiology and Deafness, The University of Manchester, United Kingdom
| | - Christopher J Plack
- Manchester Centre for Audiology and Deafness, The University of Manchester, United Kingdom
- Department of Psychology, Lancaster University, United Kingdom
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Papesh MA, Fowler L, Pesa SR, Frederick MT. Functional Hearing Difficulties in Veterans: Retrospective Chart Review of Auditory Processing Assessments in the VA Health Care System. Am J Audiol 2023; 32:101-118. [PMID: 36599099 DOI: 10.1044/2022_aja-22-00117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE Approximately 23 million Americans might have functional hearing difficulties (FHDs) that are not well explained by their audiometric thresholds. Clinical management of patients with FHDs is the subject of considerable debate, with few evidence-based guidelines to direct patient care. A better understanding of the characteristics of patients who seek help for FHDs, as well as current audiological management practices, is needed to direct research efforts to the areas greatest opportunity for advancement of clinical care. METHOD A retrospective chart review was conducted examining the medical records of a random sample of 100 Veterans who underwent auditory processing assessments across the VA Health Care System between 2008 and 2020. RESULTS Patients were young to middle-age, often with previous traumatic brain injury or blast exposure. Mental health, sleep, and pain disorders were common. No consistent relationships emerged between specific patient factors and domains of auditory processing deficits. Low-gain hearing aids were provided to 35 patients, 69% of whom continued wearing their hearing aids for at least 2 years. CONCLUSION Future research should address the potential overlap in symptoms and treatment for comorbid health conditions and FHDs, as well as the conditions underlying successful hearing aid use in this patient population.
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Affiliation(s)
- Melissa A Papesh
- VA RR&D National Center for Rehabilitative Auditory Research, VA Portland Health Care System, OR
- Department of Otolaryngology - Head and Neck Surgery, Oregon Health and Science University, Portland
| | - Lora Fowler
- Department of Communication Sciences and Disorders, Idaho State University, Pocatello
| | - Stephanie R Pesa
- VA Portland Audiology and Speech and Language Pathology Service, VA Portland Health Care System, OR
| | - Melissa T Frederick
- VA RR&D National Center for Rehabilitative Auditory Research, VA Portland Health Care System, OR
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Auditory Electrophysiological and Perceptual Measures in Student Musicians with High Sound Exposure. Diagnostics (Basel) 2023; 13:diagnostics13050934. [PMID: 36900080 PMCID: PMC10000734 DOI: 10.3390/diagnostics13050934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/05/2022] [Accepted: 02/26/2023] [Indexed: 03/06/2023] Open
Abstract
This study aimed to determine (a) the influence of noise exposure background (NEB) on the peripheral and central auditory system functioning and (b) the influence of NEB on speech recognition in noise abilities in student musicians. Twenty non-musician students with self-reported low NEB and 18 student musicians with self-reported high NEB completed a battery of tests that consisted of physiological measures, including auditory brainstem responses (ABRs) at three different stimulus rates (11.3 Hz, 51.3 Hz, and 81.3 Hz), and P300, and behavioral measures including conventional and extended high-frequency audiometry, consonant-vowel nucleus-consonant (CNC) word test and AzBio sentence test for assessing speech perception in noise abilities at -9, -6, -3, 0, and +3 dB signal to noise ratios (SNRs). The NEB was negatively associated with performance on the CNC test at all five SNRs. A negative association was found between NEB and performance on the AzBio test at 0 dB SNR. No effect of NEB was found on the amplitude and latency of P300 and the ABR wave I amplitude. More investigations of larger datasets with different NEB and longitudinal measurements are needed to investigate the influence of NEB on word recognition in noise and to understand the specific cognitive processes contributing to the impact of NEB on word recognition in noise.
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Morse K, Vander Werff KR. Onset-offset cortical auditory evoked potential amplitude differences indicate auditory cortical hyperactivity and reduced inhibition in people with tinnitus. Clin Neurophysiol 2023; 149:223-233. [PMID: 36963993 DOI: 10.1016/j.clinph.2023.02.164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 12/26/2022] [Accepted: 02/05/2023] [Indexed: 02/25/2023]
Abstract
OBJECTIVE The current study investigates evidence of hypothesized reduced central inhibition and/or increased excitation in individuals with tinnitus by evaluating cortical auditory onset versus offset responses. METHODS Cortical auditory evoked potentials (CAEPs) were recorded to the onset and offset of 3-second white noise stimuli in tinnitus and control groups matched in pairs by age, hearing, and sex (n = 26 total). Independent t-tests and 2-way mixed model ANOVA were used to evaluate onset-offset differences in amplitude, area, and latency of CAEP components by group. The predictive influence of tinnitus presence and associated participant characteristics on CAEP outcomes was assessed by multiple regression proportional reduction in error. RESULTS The tinnitus group had significantly larger onset minus offset P2 amplitudes (ΔP2 amplitudes) than control group participants. No other component variables differed significantly. ΔP2 amplitude was best predicted by tinnitus status and not significantly influenced by other variables such as hearing loss or age. CONCLUSIONS Hypothesized reduced central inhibition and/or increased excitation in tinnitus participants was partially supported by a group difference in ΔP2 amplitude. SIGNIFICANCE This was the first study to evaluate CAEP onset minus offset differences to investigate changes in central excitation/inhibition in individuals with tinnitus versus controls in matched groups.
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Affiliation(s)
- Kenneth Morse
- West Virginia University, Division of Communication Sciences and Disorders, USA.
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21
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Gómez-Álvarez M, Johannesen PT, Coelho-de-Sousa SL, Klump GM, Lopez-Poveda EA. The Relative Contribution of Cochlear Synaptopathy and Reduced Inhibition to Age-Related Hearing Impairment for People With Normal Audiograms. Trends Hear 2023; 27:23312165231213191. [PMID: 37956654 PMCID: PMC10644751 DOI: 10.1177/23312165231213191] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 10/18/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
Older people often show auditory temporal processing deficits and speech-in-noise intelligibility difficulties even when their audiogram is clinically normal. The causes of such problems remain unclear. Some studies have suggested that for people with normal audiograms, age-related hearing impairments may be due to a cognitive decline, while others have suggested that they may be caused by cochlear synaptopathy. Here, we explore an alternative hypothesis, namely that age-related hearing deficits are associated with decreased inhibition. For human adults (N = 30) selected to cover a reasonably wide age range (25-59 years), with normal audiograms and normal cognitive function, we measured speech reception thresholds in noise (SRTNs) for disyllabic words, gap detection thresholds (GDTs), and frequency modulation detection thresholds (FMDTs). We also measured the rate of growth (slope) of auditory brainstem response wave-I amplitude with increasing level as an indirect indicator of cochlear synaptopathy, and the interference inhibition score in the Stroop color and word test (SCWT) as a proxy for inhibition. As expected, performance in the auditory tasks worsened (SRTNs, GDTs, and FMDTs increased), and wave-I slope and SCWT inhibition scores decreased with ageing. Importantly, SRTNs, GDTs, and FMDTs were not related to wave-I slope but worsened with decreasing SCWT inhibition. Furthermore, after partialling out the effect of SCWT inhibition, age was no longer related to SRTNs or GDTs and became less strongly related to FMDTs. Altogether, results suggest that for people with normal audiograms, age-related deficits in auditory temporal processing and speech-in-noise intelligibility are mediated by decreased inhibition rather than cochlear synaptopathy.
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Affiliation(s)
- Marcelo Gómez-Álvarez
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Peter T. Johannesen
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Sónia L. Coelho-de-Sousa
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Georg M. Klump
- Department of Neuroscience and Cluster of Excellence “Hearing4all”, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Enrique A. Lopez-Poveda
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
- Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, Salamanca, Spain
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Shehabi AM, Prendergast G, Guest H, Plack CJ. Binaural temporal coding and the middle ear muscle reflex in audiometrically normal young adults. Hear Res 2023; 427:108663. [PMID: 36502543 DOI: 10.1016/j.heares.2022.108663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 11/11/2022] [Accepted: 11/29/2022] [Indexed: 12/07/2022]
Abstract
Noise exposure may damage the synapses that connect inner hair cells with auditory nerve fibers, before outer hair cells are lost. In humans, this cochlear synaptopathy (CS) is thought to decrease the fidelity of peripheral auditory temporal coding. In the current study, the primary hypothesis was that higher middle ear muscle reflex (MEMR) thresholds, as a proxy measure of CS, would be associated with smaller values of the binaural intelligibility level difference (BILD). The BILD, which is a measure of binaural temporal coding, is defined here as the difference in thresholds between the diotic and the antiphasic versions of the digits in noise (DIN) test. This DIN BILD may control for factors unrelated to binaural temporal coding such as linguistic, central auditory, and cognitive factors. Fifty-six audiometrically normal adults (34 females) aged 18 - 30 were tested. The test battery included standard pure tone audiometry, tympanometry, MEMR using a 2 kHz elicitor and 226 Hz and 1 kHz probes, the Noise Exposure Structured Interview, forward digit span test, extended high frequency (EHF) audiometry, and diotic and antiphasic DIN tests. The study protocol was pre-registered prior to data collection. MEMR thresholds did not predict the DIN BILD. Secondary analyses showed no association between MEMR thresholds and the individual diotic and antiphasic DIN thresholds. Greater lifetime noise exposure was non-significantly associated with higher MEMR thresholds, larger DIN BILD values, and lower (better) antiphasic DIN thresholds, but not with diotic DIN thresholds, nor with EHF thresholds. EHF thresholds were associated with neither MEMR thresholds nor any of the DIN outcomes, including the DIN BILD. Results provide no evidence that young, audiometrically normal people incur CS with impacts on binaural temporal processing.
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Affiliation(s)
- Adnan M Shehabi
- Manchester Centre for Audiology and Deafness, University of Manchester, UK; Department of Audiology and Speech Therapy, Birzeit University, Palestine.
| | | | - Hannah Guest
- Manchester Centre for Audiology and Deafness, University of Manchester, UK
| | - Christopher J Plack
- Manchester Centre for Audiology and Deafness, University of Manchester, UK; Department of Psychology, Lancaster University, UK
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Modeling temporal information encoding by the population of fibers in the healthy and synaptopathic auditory nerve. Hear Res 2022; 426:108621. [PMID: 36182814 DOI: 10.1016/j.heares.2022.108621] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 11/23/2022]
Abstract
We report a theoretical study aimed at investigating the impact of cochlear synapse loss (synaptopathy) on the encoding of the envelope (ENV) and temporal fine structure (TFS) of sounds by the population of auditory nerve fibers. A computational model was used to simulate auditory-nerve spike trains evoked by sinusoidally amplitude-modulated (AM) tones at 10 Hz with various carrier frequencies and levels. The model included 16 cochlear channels with characteristic frequencies (CFs) from 250 Hz to 8 kHz. Each channel was innervated by 3, 4 and 10 fibers with low (LSR), medium (MSR), and high spontaneous rates (HSR), respectively. For each channel, spike trains were collapsed into three separate 'population' post-stimulus time histograms (PSTHs), one per fiber type. Information theory was applied to reconstruct the stimulus waveform, ENV, and TFS from one or more PSTHs in a mathematically optimal way. The quality of the reconstruction was regarded as an estimate of the information present in the used PSTHs. Various synaptopathy scenarios were simulated by removing fibers of specific types and/or cochlear regions before stimulus reconstruction. We found that the TFS was predominantly encoded by HSR fibers at all stimulus carrier frequencies and levels. The encoding of the ENV was more complex. At lower levels, the ENV was predominantly encoded by HSR fibers with CFs near the stimulus carrier frequency. At higher levels, the ENV was equally well or better encoded by HSR fibers with CFs different from the AM carrier frequency as by LSR fibers with CFs at the carrier frequency. Altogether, findings suggest that a healthy population of HSR fibers (i.e., including fibers with CFs around and remote from the AM carrier frequency) might be sufficient to encode the ENV and TFS over a wide range of stimulus levels. Findings are discussed regarding their relevance for diagnosing synaptopathy using non-invasive ENV- and TFS-based measures.
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Drakopoulos F, Vasilkov V, Osses Vecchi A, Wartenberg T, Verhulst S. Model-based hearing-enhancement strategies for cochlear synaptopathy pathologies. Hear Res 2022; 424:108569. [DOI: 10.1016/j.heares.2022.108569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/07/2022] [Accepted: 07/12/2022] [Indexed: 11/04/2022]
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Shehabi AM, Prendergast G, Plack CJ. The Relative and Combined Effects of Noise Exposure and Aging on Auditory Peripheral Neural Deafferentation: A Narrative Review. Front Aging Neurosci 2022; 14:877588. [PMID: 35813954 PMCID: PMC9260498 DOI: 10.3389/fnagi.2022.877588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
Animal studies have shown that noise exposure and aging cause a reduction in the number of synapses between low and medium spontaneous rate auditory nerve fibers and inner hair cells before outer hair cell deterioration. This noise-induced and age-related cochlear synaptopathy (CS) is hypothesized to compromise speech recognition at moderate-to-high suprathreshold levels in humans. This paper evaluates the evidence on the relative and combined effects of noise exposure and aging on CS, in both animals and humans, using histopathological and proxy measures. In animal studies, noise exposure seems to result in a higher proportion of CS (up to 70% synapse loss) compared to aging (up to 48% synapse loss). Following noise exposure, older animals, depending on their species, seem to either exhibit significant or little further synapse loss compared to their younger counterparts. In humans, temporal bone studies suggest a possible age- and noise-related auditory nerve fiber loss. Based on the animal data obtained from different species, we predict that noise exposure may accelerate age-related CS to at least some extent in humans. In animals, noise-induced and age-related CS in separation have been consistently associated with a decreased amplitude of wave 1 of the auditory brainstem response, reduced middle ear muscle reflex strength, and degraded temporal processing as demonstrated by lower amplitudes of the envelope following response. In humans, the individual effects of noise exposure and aging do not seem to translate clearly into deficits in electrophysiological, middle ear muscle reflex, and behavioral measures of CS. Moreover, the evidence on the combined effects of noise exposure and aging on peripheral neural deafferentation in humans using electrophysiological and behavioral measures is even more sparse and inconclusive. Further research is necessary to establish the individual and combined effects of CS in humans using temporal bone, objective, and behavioral measures.
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Affiliation(s)
- Adnan M. Shehabi
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, United Kingdom
- Department of Audiology and Speech Therapy, Birzeit University, Birzeit, Palestine
| | - Garreth Prendergast
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, United Kingdom
| | - Christopher J. Plack
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, United Kingdom
- Department of Psychology, Lancaster University, Lancaster, United Kingdom
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Le Prell CG. Prevention of Noise-Induced Hearing Loss Using Investigational Medicines for the Inner Ear: Previous Trial Outcomes Should Inform Future Trial Design. Antioxid Redox Signal 2022; 36:1171-1202. [PMID: 34346254 PMCID: PMC9221155 DOI: 10.1089/ars.2021.0166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 07/25/2021] [Indexed: 11/13/2022]
Abstract
Significance: Noise-induced hearing loss (NIHL) is an important public health issue resulting in decreased quality of life for affected individuals, and significant costs to employers and governmental agencies. Recent Advances: Advances in the mechanistic understanding of NIHL have prompted a growing number of proposed, in-progress, and completed clinical trials for possible protections against NIHL via antioxidants and other drug agents. Thirty-one clinical trials evaluating prevention of either temporary or permanent NIHL were identified and are reviewed. Critical Issues: This review revealed little consistency in the noise-exposed populations in which drugs are evaluated or the primary outcomes used to measure NIHL prevention. Changes in pure-tone thresholds were the most common primary outcomes; specific threshold metrics included both average hearing loss and incidence of significant hearing loss. Changes in otoacoustic emission (OAE) amplitude were relatively common secondary outcomes. Extended high-frequency (EHF) hearing and speech-in-noise perception are commonly adversely affected by noise exposure but are not consistently included in clinical trials assessing prevention of NIHL. Future Directions: Multiple criteria are available for monitoring NIHL, but the specific criterion to be used to define clinically significant otoprotection remains a topic of discussion. Audiogram-based primary outcome measures can be combined with secondary outcomes, including OAE amplitude, EHF hearing, speech-in-noise testing, tinnitus surveys, and patient-reported outcomes. Standardization of test protocols for the above primary and secondary outcomes, and associated reporting criterion for each, would facilitate clinical trial design and comparison of results across investigational drug agents. Antioxid. Redox Signal. 36, 1171-1202.
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Affiliation(s)
- Colleen G. Le Prell
- Department of Speech, Language, and Hearing Science, University of Texas at Dallas, Richardson, Texas, USA
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Shehabi AM, Prendergast G, Guest H, Plack CJ. The Effect of Lifetime Noise Exposure and Aging on Speech-Perception-in-Noise Ability and Self-Reported Hearing Symptoms: An Online Study. Front Aging Neurosci 2022; 14:890010. [PMID: 35711902 PMCID: PMC9195834 DOI: 10.3389/fnagi.2022.890010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/28/2022] [Indexed: 12/03/2022] Open
Abstract
Animal research shows that aging and excessive noise exposure damage cochlear outer hair cells, inner hair cells, and the synapses connecting inner hair cells with the auditory nerve. This may translate into auditory symptoms such as difficulty understanding speech in noise, tinnitus, and hyperacusis. The current study, using a novel online approach, assessed and quantified the effects of lifetime noise exposure and aging on (i) speech-perception-in-noise (SPiN) thresholds, (ii) self-reported hearing ability, and (iii) the presence of tinnitus. Secondary aims involved documenting the effects of lifetime noise exposure and aging on tinnitus handicap and the severity of hyperacusis. Two hundred and ninety-four adults with no past diagnosis of hearing or memory impairments were recruited online. Participants were assigned into two groups: 217 "young" (age range: 18-35 years, females: 151) and 77 "older" (age range: 50-70 years, females: 50). Participants completed a set of online instruments including an otologic health and demographic questionnaire, a dementia screening tool, forward and backward digit span tests, a noise exposure questionnaire, the Khalfa hyperacusis questionnaire, the short-form of the Speech, Spatial, and Qualities of Hearing scale, the Tinnitus Handicap Inventory, a digits-in-noise test, and a Coordinate Response Measure speech-perception test. Analyses controlled for sex and cognitive function as reflected by the digit span. A detailed protocol was pre-registered, to guard against "p-hacking" of this extensive dataset. Lifetime noise exposure did not predict SPiN thresholds, self-reported hearing ability, or the presence of tinnitus in either age group. Exploratory analyses showed that worse hyperacusis scores, and a greater prevalence of tinnitus, were associated significantly with high lifetime noise exposure in the young, but not in the older group. Age was a significant predictor of SPiN thresholds and the presence of tinnitus, but not of self-reported hearing ability, tinnitus handicap, or severity of hyperacusis. Consistent with several lab studies, our online-derived data suggest that older adults with no diagnosis of hearing impairment have a poorer SPiN ability and a higher risk of tinnitus than their younger counterparts. Moreover, lifetime noise exposure may increase the risk of tinnitus and the severity of hyperacusis in young adults with no diagnosis of hearing impairment.
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Affiliation(s)
- Adnan M. Shehabi
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, United Kingdom
- Department of Audiology and Speech Therapy, Birzeit University, Birzeit, Palestine
| | - Garreth Prendergast
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, United Kingdom
| | - Hannah Guest
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, United Kingdom
| | - Christopher J. Plack
- Manchester Centre for Audiology and Deafness, University of Manchester, Manchester, United Kingdom
- Department of Psychology, Lancaster University, Lancaster, United Kingdom
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Harris KC, Bao J. Optimizing non-invasive functional markers for cochlear deafferentation based on electrocochleography and auditory brainstem responses. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:2802. [PMID: 35461487 PMCID: PMC9034896 DOI: 10.1121/10.0010317] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/22/2022] [Accepted: 04/08/2022] [Indexed: 06/14/2023]
Abstract
Accumulating evidence suggests that cochlear deafferentation may contribute to suprathreshold deficits observed with or without elevated hearing thresholds, and can lead to accelerated age-related hearing loss. Currently there are no clinical diagnostic tools to detect human cochlear deafferentation in vivo. Preclinical studies using a combination of electrophysiological and post-mortem histological methods clearly demonstrate cochlear deafferentation including myelination loss, mitochondrial damages in spiral ganglion neurons (SGNs), and synaptic loss between inner hair cells and SGNs. Since clinical diagnosis of human cochlear deafferentation cannot include post-mortem histological quantification, various attempts based on functional measurements have been made to detect cochlear deafferentation. So far, those efforts have led to inconclusive results. Two major obstacles to the development of in vivo clinical diagnostics include a lack of standardized methods to validate new approaches and characterize the normative range of repeated measurements. In this overview, we examine strategies from previous studies to detect cochlear deafferentation from electrocochleography and auditory brainstem responses. We then summarize possible approaches to improve these non-invasive functional methods for detecting cochlear deafferentation with a focus on cochlear synaptopathy. We identify conceptual approaches that should be tested to associate unique electrophysiological features with cochlear deafferentation.
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Affiliation(s)
- Kelly C Harris
- Department of Otolaryngology, Head & Neck Surgery, Medical University of South Carolina, 135 Rutledge Avenue, MSC 550, Charleston, South Carolina 29425, USA
| | - Jianxin Bao
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio 44272, USA
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29
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Marrufo-Pérez MI, Lopez-Poveda EA. Adaptation to noise in normal and impaired hearing. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:1741. [PMID: 35364964 DOI: 10.1121/10.0009802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 02/26/2022] [Indexed: 06/14/2023]
Abstract
Many aspects of hearing function are negatively affected by background noise. Listeners, however, have some ability to adapt to background noise. For instance, the detection of pure tones and the recognition of isolated words embedded in noise can improve gradually as tones and words are delayed a few hundred milliseconds in the noise. While some evidence suggests that adaptation to noise could be mediated by the medial olivocochlear reflex, adaptation can occur for people who do not have a functional reflex. Since adaptation can facilitate hearing in noise, and hearing in noise is often harder for hearing-impaired than for normal-hearing listeners, it is conceivable that adaptation is impaired with hearing loss. It remains unclear, however, if and to what extent this is the case, or whether impaired adaptation contributes to the greater difficulties experienced by hearing-impaired listeners understanding speech in noise. Here, we review adaptation to noise, the mechanisms potentially contributing to this adaptation, and factors that might reduce the ability to adapt to background noise, including cochlear hearing loss, cochlear synaptopathy, aging, and noise exposure. The review highlights few knowns and many unknowns about adaptation to noise, and thus paves the way for further research on this topic.
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Affiliation(s)
- Miriam I Marrufo-Pérez
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Calle Pintor Fernando Gallego 1, 37007 Salamanca, Spain
| | - Enrique A Lopez-Poveda
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Calle Pintor Fernando Gallego 1, 37007 Salamanca, Spain
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Auditory Brainstem Response Wave I Amplitude Has Limited Clinical Utility in Diagnosing Tinnitus in Humans. Brain Sci 2022; 12:brainsci12020142. [PMID: 35203907 PMCID: PMC8870703 DOI: 10.3390/brainsci12020142] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/13/2022] [Accepted: 01/18/2022] [Indexed: 11/25/2022] Open
Abstract
Animal studies have discovered that noise, even at levels that produce no permanent threshold shift, may cause cochlear damage and selective nerve degeneration. A hallmark of such damage, or synaptopathy, is recovered threshold but reduced suprathreshold amplitude for the auditory brainstem response (ABR) wave I. The objective of the present study is to evaluate whether the ABR wave I amplitude or slope can be used to diagnose tinnitus in humans. A total of 43 human subjects, consisting of 21 with tinnitus and 22 without tinnitus, participated in the study. The subjects were on average 44 ± 24 (standard deviation) years old and 16 were female; a subgroup of 19 were young adults with normal audiograms from 125 to 8000 Hz. The ABR was measured using ear canal recording tiptrodes for clicks, 1000, 4000 and 8000 Hz tone bursts at 30, 50, and 70 dB nHL. Compared with control subjects, tinnitus subjects did not show reduced ABR wave I amplitude or slope in either the entire group of 21 tinnitus subjects or a subset of tinnitus subjects with normal audiograms. Despite the small sample size and diverse tinnitus population, the present result suggests that low signal-to-noise ratios in non-invasive measurement of the ABR limit its clinical utility in diagnosing tinnitus in humans.
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31
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Evidence for Loss of Activity in Low-Spontaneous-Rate Auditory Nerve Fibers of Older Adults. J Assoc Res Otolaryngol 2022; 23:273-284. [PMID: 35020090 PMCID: PMC8964899 DOI: 10.1007/s10162-021-00827-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 11/29/2021] [Indexed: 10/19/2022] Open
Abstract
Auditory function declines with age, as evidenced by communication difficulties in challenging listening environments for older adults. Declining auditory function may arise, in part, from an age-related loss and/or inactivity of low-spontaneous-rate (SR) auditory nerve (AN) fibers, a subgroup of neurons important for suprathreshold processing. Compared to high-SR fibers, low-SR fibers take longer to recover from prior stimulation. Taking advantage of this difference, the forward-masked recovery function paradigm estimates the relative proportions of low- and high-SR fibers in the AN by quantifying the time needed for AN responses to recover from prior stimulation (ΔTrecovery). Due to the slower recovery of low-SR fibers, ANs that need more time to fully recover (longer ΔTrecovery) are estimated to have a larger proportion of low-SR fibers than ANs that need less time (shorter ΔTrecovery). To test the hypothesis that low-SR fiber activity is reduced in older humans, the current study assessed recovery functions in 32 older and 16 younger adults using the compound action potential. Results show that ΔTrecovery is shorter for older adults than for younger adults, consistent with a theorized age-related loss and/or inactivity of low-SR fibers. ΔTrecovery did not differ between individuals with and without a prior history of noise exposure as assessed by self-report. This study is the first to successfully assess forward-masked recovery functions in both younger and older adults and provides important insights into the structural and functional changes occurring in the AN with increasing age.
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Cutting Through the Noise: Noise-Induced Cochlear Synaptopathy and Individual Differences in Speech Understanding Among Listeners With Normal Audiograms. Ear Hear 2022; 43:9-22. [PMID: 34751676 PMCID: PMC8712363 DOI: 10.1097/aud.0000000000001147] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Following a conversation in a crowded restaurant or at a lively party poses immense perceptual challenges for some individuals with normal hearing thresholds. A number of studies have investigated whether noise-induced cochlear synaptopathy (CS; damage to the synapses between cochlear hair cells and the auditory nerve following noise exposure that does not permanently elevate hearing thresholds) contributes to this difficulty. A few studies have observed correlations between proxies of noise-induced CS and speech perception in difficult listening conditions, but many have found no evidence of a relationship. To understand these mixed results, we reviewed previous studies that have examined noise-induced CS and performance on speech perception tasks in adverse listening conditions in adults with normal or near-normal hearing thresholds. Our review suggests that superficially similar speech perception paradigms used in previous investigations actually placed very different demands on sensory, perceptual, and cognitive processing. Speech perception tests that use low signal-to-noise ratios and maximize the importance of fine sensory details- specifically by using test stimuli for which lexical, syntactic, and semantic cues do not contribute to performance-are more likely to show a relationship to estimated CS levels. Thus, the current controversy as to whether or not noise-induced CS contributes to individual differences in speech perception under challenging listening conditions may be due in part to the fact that many of the speech perception tasks used in past studies are relatively insensitive to CS-induced deficits.
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Henry KS. Animal models of hidden hearing loss: Does auditory-nerve-fiber loss cause real-world listening difficulties? Mol Cell Neurosci 2022; 118:103692. [PMID: 34883241 PMCID: PMC8928575 DOI: 10.1016/j.mcn.2021.103692] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 12/01/2021] [Accepted: 12/02/2021] [Indexed: 01/03/2023] Open
Abstract
Afferent innervation of the cochlea by the auditory nerve declines during aging and potentially after sound overexposure, producing the common pathology known as cochlear synaptopathy. Auditory-nerve-fiber loss is difficult to detect with the clinical audiogram and has been proposed to cause 'hidden hearing loss' including impaired speech-in-noise perception. While evidence that auditory-nerve-fiber loss causes hidden hearing loss in humans is controversial, behavioral animal models hold promise to rigorously test this hypothesis because neural lesions can be induced and histologically validated. Here, we review recent animal behavioral studies on the impact of auditory-nerve-fiber loss on perception in a range of species. We first consider studies of tinnitus and hyperacusis inferred from acoustic startle reflexes, followed by a review of operant-conditioning studies of the audiogram, temporal integration for tones of varying duration, temporal resolution of gaps in noise, and tone-in-noise detection. Studies quantifying the audiogram show that tone-in-quiet sensitivity is unaffected by auditory-nerve-fiber loss unless neural lesions exceed 80%, at which point large deficits are possible. Changes in other aspects of perception, which were typically investigated for moderate-to-severe auditory-nerve-fiber loss of 50-70%, appear heterogeneous across studies and might be small compared to impairment caused by hair-cell pathologies. Future studies should pursue recent findings that behavioral sensitivity to brief tones and silent gaps in noise may be particularly vulnerable to auditory-nerve-fiber loss. Furthermore, aspects of auditory perception linked to central inhibition and fine neural response timing, such as modulation masking release and spatial hearing, may be productive directions for further animal behavioral research.
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Affiliation(s)
- Kenneth S Henry
- Departments of Otolaryngology, Biomedical Engineering, and Neuroscience, University of Rochester, Rochester, NY, USA.
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Carcagno S, Plack CJ. Relations between speech-reception, psychophysical temporal processing, and subcortical electrophysiological measures of auditory function in humans. Hear Res 2022; 417:108456. [PMID: 35149333 PMCID: PMC8935383 DOI: 10.1016/j.heares.2022.108456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 01/05/2022] [Accepted: 01/27/2022] [Indexed: 11/04/2022]
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35
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Bramhall NF. Use of the auditory brainstem response for assessment of cochlear synaptopathy in humans. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:4440. [PMID: 34972291 PMCID: PMC10880747 DOI: 10.1121/10.0007484] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 11/07/2021] [Indexed: 06/14/2023]
Abstract
Although clinical use of the auditory brainstem response (ABR) to detect retrocochlear disorders has been largely replaced by imaging in recent years, the discovery of cochlear synaptopathy has thrown this foundational measure of auditory function back into the spotlight. Whereas modern imaging now allows for the noninvasive detection of vestibular schwannomas, imaging technology is not currently capable of detecting cochlear synaptopathy, the loss of the synaptic connections between the inner hair cells and afferent auditory nerve fibers. However, animal models indicate that the amplitude of the first wave of the ABR, a far-field evoked potential generated by the synchronous firing of auditory nerve fibers, is highly correlated with synaptic integrity. This has led to many studies investigating the use of the ABR as a metric of synaptopathy in humans. However, these studies have yielded mixed results, leading to a lack of consensus about the utility of the ABR as an indicator of synaptopathy. This review summarizes the animal and human studies that have investigated the ABR as a measure of cochlear synaptic function, discusses factors that may have contributed to the mixed findings and the lessons learned, and provides recommendations for future use of this metric in the research and clinical settings.
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Affiliation(s)
- Naomi F Bramhall
- Veterans Affairs (VA) Rehabilitation Research & Development Service (RR&D) National Center for Rehabilitative Auditory Research (NCRAR), VA Portland Health Care System Portland, Oregon 97239, USA
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36
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Settibhaktini H, Heinz MG, Chintanpalli A. Modeling the effects of age and hearing loss on concurrent vowel scores. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:3581. [PMID: 34852572 PMCID: PMC8594952 DOI: 10.1121/10.0007046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 10/09/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
A difference in fundamental frequency (F0) between two vowels is an important segregation cue prior to identifying concurrent vowels. To understand the effects of this cue on identification due to age and hearing loss, Chintanpalli, Ahlstrom, and Dubno [(2016). J. Acoust. Soc. Am. 140, 4142-4153] collected concurrent vowel scores across F0 differences for younger adults with normal hearing (YNH), older adults with normal hearing (ONH), and older adults with hearing loss (OHI). The current modeling study predicts these concurrent vowel scores to understand age and hearing loss effects. The YNH model cascaded the temporal responses of an auditory-nerve model from Bruce, Efrani, and Zilany [(2018). Hear. Res. 360, 40-45] with a modified F0-guided segregation algorithm from Meddis and Hewitt [(1992). J. Acoust. Soc. Am. 91, 233-245] to predict concurrent vowel scores. The ONH model included endocochlear-potential loss, while the OHI model also included hair cell damage; however, both models incorporated cochlear synaptopathy, with a larger effect for OHI. Compared with the YNH model, concurrent vowel scores were reduced across F0 differences for ONH and OHI models, with the lowest scores for OHI. These patterns successfully captured the age and hearing loss effects in the concurrent-vowel data. The predictions suggest that the inability to utilize an F0-guided segregation cue, resulting from peripheral changes, may reduce scores for ONH and OHI listeners.
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Affiliation(s)
- Harshavardhan Settibhaktini
- Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science, Pilani Campus, Vidya Vihar, Pilani, Rajasthan 333031, India
| | - Michael G Heinz
- Department of Speech, Language and Hearing Sciences, and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907-2028, USA
| | - Ananthakrishna Chintanpalli
- Department of Electrical and Electronics Engineering, Birla Institute of Technology and Science, Pilani Campus, Vidya Vihar, Pilani, Rajasthan 333031, India
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Middle Ear Muscle Reflex and Word Recognition in "Normal-Hearing" Adults: Evidence for Cochlear Synaptopathy? Ear Hear 2021; 41:25-38. [PMID: 31584501 DOI: 10.1097/aud.0000000000000804] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Permanent threshold elevation after noise exposure, ototoxic drugs, or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of synapses between sensory cells and auditory nerve fibers. The silencing of these neurons, especially those with high thresholds and low spontaneous rates, degrades auditory processing and may contribute to difficulties in understanding speech in noise. Although cochlear synaptopathy can be diagnosed in animals by measuring suprathreshold auditory brainstem responses, its diagnosis in humans remains a challenge. In mice, cochlear synaptopathy is also correlated with measures of middle ear muscle (MEM) reflex strength, possibly because the missing high-threshold neurons are important drivers of this reflex. The authors hypothesized that measures of the MEM reflex might be better than other assays of peripheral function in predicting difficulties hearing in difficult listening environments in human subjects. DESIGN The authors recruited 165 normal-hearing healthy subjects, between 18 and 63 years of age, with no history of ear or hearing problems, no history of neurologic disorders, and unremarkable otoscopic examinations. Word recognition in quiet and in difficult listening situations was measured in four ways: using isolated words from the Northwestern University auditory test number six corpus with either (a) 0 dB signal to noise, (b) 45% time compression with reverberation, or (c) 65% time compression with reverberation, and (d) with a modified version of the QuickSIN. Audiometric thresholds were assessed at standard and extended high frequencies. Outer hair cell function was assessed by distortion product otoacoustic emissions (DPOAEs). Middle ear function and reflexes were assessed using three methods: the acoustic reflex threshold as measured clinically, wideband tympanometry as measured clinically, and a custom wideband method that uses a pair of click probes flanking an ipsilateral noise elicitor. Other aspects of peripheral auditory function were assessed by measuring click-evoked gross potentials, that is, summating potential (SP) and action potential (AP) from ear canal electrodes. RESULTS After adjusting for age and sex, word recognition scores were uncorrelated with audiometric or DPOAE thresholds, at either standard or extended high frequencies. MEM reflex thresholds were significantly correlated with scores on isolated word recognition, but not with the modified version of the QuickSIN. The highest pairwise correlations were seen using the custom assay. AP measures were correlated with some of the word scores, but not as highly as seen for the MEM custom assay, and only if amplitude was measured from SP peak to AP peak, rather than baseline to AP peak. The highest pairwise correlations with word scores, on all four tests, were seen with the SP/AP ratio, followed closely by SP itself. When all predictor variables were combined in a stepwise multivariate regression, SP/AP dominated models for all four word score outcomes. MEM measures only enhanced the adjusted r values for the 45% time compression test. The only other predictors that enhanced model performance (and only for two outcome measures) were measures of interaural threshold asymmetry. CONCLUSIONS Results suggest that, among normal-hearing subjects, there is a significant peripheral contribution to diminished hearing performance in difficult listening environments that is not captured by either threshold audiometry or DPOAEs. The significant univariate correlations between word scores and either SP/AP, SP, MEM reflex thresholds, or AP amplitudes (in that order) are consistent with a type of primary neural degeneration. However, interpretation is clouded by uncertainty as to the mix of pre- and postsynaptic contributions to the click-evoked SP. None of the assays presented here has the sensitivity to diagnose neural degeneration on a case-by-case basis; however, these tests may be useful in longitudinal studies to track accumulation of neural degeneration in individual subjects.
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Efficacy of behavioral audiological tests in identifying cochlear synaptopathy: a systematic review. Eur Arch Otorhinolaryngol 2021; 279:577-594. [PMID: 34106328 DOI: 10.1007/s00405-021-06927-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/01/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE Cochlear synaptopathy or hidden hearing loss is difficult to assess due to the lack of sensitivity with standard audiological tests. Poor speech perception, especially in the presence of noise or tinnitus, is the most common complaint of these patients. The purpose of this systematic review is to identify articles in peer-reviewed journals that used behavioral measures in the effective assessment of cochlear synaptopathy or hidden hearing loss. METHODS The manuscripts were searched in various international databases, and the manuscripts were screened based on titles, abstracts, and full-length content. A total of 14 human studies were selected after the appropriate exclusion of other articles. RESULTS Results showed that high-frequency audiometry could be used for the early identification of cochlear synaptopathy. The tone in noise detection test can also be added in the test battery along with speech perception in noise. The amplitude modulation detection test, interaural phase difference, and differential sensitivity tests require more research before using them for the assessment of cochlear synaptopathy or hidden hearing loss. CONCLUSIONS Self-reports and questionnaires also help in determining the extent of noise exposure.
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Johannesen PT, Lopez-Poveda EA. Age-related central gain compensation for reduced auditory nerve output for people with normal audiograms, with and without tinnitus. iScience 2021; 24:102658. [PMID: 34151241 PMCID: PMC8192693 DOI: 10.1016/j.isci.2021.102658] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/24/2021] [Accepted: 05/25/2021] [Indexed: 11/30/2022] Open
Abstract
Central gain compensation for reduced auditory nerve output has been hypothesized as a mechanism for tinnitus with a normal audiogram. Here, we investigate if gain compensation occurs with aging. For 94 people (aged 12-68 years, 64 women, 7 tinnitus) with normal or close-to-normal audiograms, the amplitude of wave I of the auditory brainstem response decreased with increasing age but was not correlated with wave V amplitude after accounting for age-related subclinical hearing loss and cochlear damage, a result indicative of age-related gain compensation. The correlations between age and wave I/III or III/V amplitude ratios suggested that compensation occurs at the wave III generator site. For each one of the seven participants with non-pulsatile tinnitus, the amplitude of wave I, wave V, and the wave I/V amplitude ratio were well within the confidence limits of the non-tinnitus participants. We conclude that increased central gain occurs with aging and is not specific to tinnitus.
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Affiliation(s)
- Peter T Johannesen
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Calle Pintor Fernando Gallego 1, 37007 Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, 37007 Salamanca, Spain
| | - Enrique A Lopez-Poveda
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Calle Pintor Fernando Gallego 1, 37007 Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, 37007 Salamanca, Spain.,Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, 37007 Salamanca, Spain
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Mepani AM, Verhulst S, Hancock KE, Garrett M, Vasilkov V, Bennett K, de Gruttola V, Liberman MC, Maison SF. Envelope following responses predict speech-in-noise performance in normal-hearing listeners. J Neurophysiol 2021; 125:1213-1222. [PMID: 33656936 DOI: 10.1152/jn.00620.2020] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Permanent threshold elevation after noise exposure or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of the synapses between sensory cells and auditory nerve fibers. Silencing these neurons is likely to degrade auditory processing and may contribute to difficulties understanding speech in noisy backgrounds. Reduction of suprathreshold ABR amplitudes can be used to quantify synaptopathy in inbred mice. However, ABR amplitudes are highly variable in humans, and thus more challenging to use. Since noise-induced neuropathy preferentially targets fibers with high thresholds and low spontaneous rate and because phase locking to temporal envelopes is particularly strong in these fibers, measuring envelope following responses (EFRs) might be a more robust measure of cochlear synaptopathy. A recent auditory model further suggests that modulation of carrier tones with rectangular envelopes should be less sensitive to cochlear amplifier dysfunction and, therefore, a better metric of cochlear neural damage than sinusoidal amplitude modulation. In this study, we measure performance scores on a variety of difficult word-recognition tasks among listeners with normal audiograms and assess correlations with EFR magnitudes to rectangular versus sinusoidal modulation. Higher harmonics of EFR magnitudes evoked by a rectangular-envelope stimulus were significantly correlated with word scores, whereas those evoked by sinusoidally modulated tones did not. These results support previous reports that individual differences in synaptopathy may be a source of speech recognition variability despite the presence of normal thresholds at standard audiometric frequencies.NEW & NOTEWORTHY Recent studies suggest that millions of people may be at risk of permanent impairment from cochlear synaptopathy, the age-related and noise-induced degeneration of neural connections in the inner ear. This study examines electrophysiological responses to stimuli designed to improve detection of neural damage in subjects with normal hearing sensitivity. The resultant correlations with word recognition performance are consistent with a contribution of cochlear neural damage to deficits in hearing in noise abilities.
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Affiliation(s)
- Anita M Mepani
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts
| | - Sarah Verhulst
- Department of Information Technology, Ghent University, Ghent, Belgium
| | - Kenneth E Hancock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts.,Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts
| | - Markus Garrett
- Department of Information Technology, Ghent University, Ghent, Belgium.,Department of Medical Physics and Acoustics, University of Oldenburg, Oldenburg, Germany
| | | | - Kara Bennett
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Victor de Gruttola
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts.,Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts.,Harvard Program in Speech and Hearing Bioscience and Technology, Harvard University, Boston, Massachusetts
| | - Stéphane F Maison
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts.,Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts.,Harvard Program in Speech and Hearing Bioscience and Technology, Harvard University, Boston, Massachusetts
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Lee JH, Lee MY, Choi JE, Jung JY. Auditory Brainstem Response to Paired Click Stimulation as an Indicator of Peripheral Synaptic Health in Noise-Induced Cochlear Synaptopathy. Front Neurosci 2021; 14:596670. [PMID: 33505238 PMCID: PMC7830024 DOI: 10.3389/fnins.2020.596670] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/03/2020] [Indexed: 11/22/2022] Open
Abstract
Introduction A defect in the cochlear afferent synapse between the inner hair cells and spiral ganglion neurons, after noise exposure, without changes in the hearing threshold has been reported. Animal studies on auditory evoked potentials demonstrated changes in the auditory brainstem response (ABR) measurements of peak I amplitude and the loss of synapses, which affect the temporal resolution of complex sounds. Human studies of auditory evoked potential have reported ambiguous results regarding the relationship between peak I amplitude and noise exposure. Paired click stimuli have been used to investigate the temporal processing abilities of humans and animals. In this study, we investigated the utility of measuring auditory evoked potentials in response to paired click stimuli to assess the temporal processing function of ribbon synapses in noise-induced cochlear synaptopathy. Materials and Methods Twenty-two Sprague Dawley rats were used in this study, and synaptopathy was induced by narrow-band noise exposure (16 kHz with 1 kHz bandwidth, 105 dB sound pressure level for 2 h). ABRs to tone and paired click stimuli were measured before and 1, 3, 7, and 14 days after noise exposure. For histological analyses, hair cells and ribbon synapses were immunostained and the synapses quantified. The relationships among ABR peak I amplitude, number of synapses, and ABR to paired click stimuli were examined. Results Our results showed that ABR thresholds increase 1 day after noise exposure but fully recover to baseline levels after 14 days. Further, we demonstrated test frequency-dependent decreases in peak I amplitude and the number of synapses after noise exposure. These decreases were statistically significant at frequencies of 16 and 32 kHz. However, the ABR recovery threshold to paired click stimuli increased, which represent deterioration in the ability of temporal auditory processing. Our results indicate that the ABR recovery threshold is highly correlated with ABR peak I amplitude after noise exposure. We also established a direct correlation between the ABR recovery threshold and histological findings. Conclusion The result from this study suggests that in animal studies, the ABR to paired click stimuli along with peak I amplitude has potential as an assessment tool for hidden hearing loss.
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Affiliation(s)
- Jae-Hun Lee
- Department of Otolaryngology Head and Neck Surgery College of Medicine, Dankook University, Cheonan, South Korea
| | - Min Young Lee
- Department of Otolaryngology Head and Neck Surgery College of Medicine, Dankook University, Cheonan, South Korea.,Department of Otolaryngology Head and Neck Surgery, Dankook University Hospital, Cheonan, South Korea
| | - Ji Eun Choi
- Department of Otolaryngology Head and Neck Surgery College of Medicine, Dankook University, Cheonan, South Korea.,Department of Otolaryngology Head and Neck Surgery, Dankook University Hospital, Cheonan, South Korea
| | - Jae Yun Jung
- Department of Otolaryngology Head and Neck Surgery College of Medicine, Dankook University, Cheonan, South Korea.,Department of Otolaryngology Head and Neck Surgery, Dankook University Hospital, Cheonan, South Korea
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Henry KS, Abrams KS. Normal Tone-In-Noise Sensitivity in Trained Budgerigars despite Substantial Auditory-Nerve Injury: No Evidence of Hidden Hearing Loss. J Neurosci 2021; 41:118-129. [PMID: 33177067 PMCID: PMC7786208 DOI: 10.1523/jneurosci.2104-20.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/02/2020] [Accepted: 10/24/2021] [Indexed: 02/01/2023] Open
Abstract
Loss of auditory-nerve (AN) afferent cochlear innervation is a prevalent human condition that does not affect audiometric thresholds and therefore remains largely undetectable with standard clinical tests. AN loss is widely expected to cause hearing difficulties in noise, known as "hidden hearing loss," but support for this hypothesis is controversial. Here, we used operant conditioning procedures to examine the perceptual impact of AN loss on behavioral tone-in-noise (TIN) sensitivity in the budgerigar (Melopsittacus undulatus; of either sex), an avian animal model with complex hearing abilities similar to humans. Bilateral kainic acid (KA) infusions depressed compound AN responses by 40-70% without impacting otoacoustic emissions or behavioral tone sensitivity in quiet. Surprisingly, animals with AN damage showed normal thresholds for tone detection in noise (0.1 ± 1.0 dB compared to control animals; mean difference ± SE), even under a challenging roving-level condition with random stimulus variation across trials. Furthermore, decision-variable correlations (DVCs) showed no difference for AN-damaged animals in their use of energy and envelope cues to perform the task. These results show that AN damage has less impact on TIN detection than generally expected, even under a difficult roving-level condition known to impact TIN detection in individuals with sensorineural hearing loss (SNHL). Perceptual deficits could emerge for different perceptual tasks or with greater AN loss but are potentially minor compared with those caused by SNHL.SIGNIFICANCE STATEMENT Loss of auditory-nerve (AN) cochlear innervation is a common problem in humans that does not affect audiometric thresholds on a clinical hearing test. AN loss is widely expected to cause hearing problems in noise, known as "hidden hearing loss," but existing studies are controversial. Here, using an avian animal model with complex hearing abilities similar to humans, we examined for the first time the impact of an experimentally induced AN lesion on behavioral tone sensitivity in noise. Surprisingly, AN-lesioned animals showed no difference in hearing performance in noise or detection strategy compared with controls. These results show that perceptual deficits from AN damage are smaller than generally expected, and potentially minor compared with those caused by sensorineural hearing loss (SNHL).
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Affiliation(s)
- Kenneth S Henry
- Department of Otolaryngology, University of Rochester, Rochester, New York 14642
- Department of Biomedical Engineering, University of Rochester, Rochester, New York 14642
- Department of Neuroscience, University of Rochester, Rochester, New York 14642
| | - Kristina S Abrams
- Department of Neuroscience, University of Rochester, Rochester, New York 14642
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Enhancing the sensitivity of the envelope-following response for cochlear synaptopathy screening in humans: The role of stimulus envelope. Hear Res 2020; 400:108132. [PMID: 33333426 DOI: 10.1016/j.heares.2020.108132] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/25/2020] [Accepted: 11/25/2020] [Indexed: 02/07/2023]
Abstract
Auditory de-afferentation, a permanent reduction in the number of inner-hair-cells and auditory-nerve synapses due to cochlear damage or synaptopathy, can reliably be quantified using temporal bone histology and immunostaining. However, there is an urgent need for non-invasive markers of synaptopathy to study its perceptual consequences in live humans and to develop effective therapeutic interventions. While animal studies have identified candidate auditory-evoked-potential (AEP) markers for synaptopathy, their interpretation in humans has suffered from translational issues related to neural generator differences, unknown hearing-damage histopathologies or lack of measurement sensitivity. To render AEP-based markers of synaptopathy more sensitive and differential to the synaptopathy aspect of sensorineural hearing loss, we followed a combined computational and experimental approach. Starting from the known characteristics of auditory-nerve physiology, we optimized the stimulus envelope to stimulate the available auditory-nerve population optimally and synchronously to generate strong envelope-following-responses (EFRs). We further used model simulations to explore which stimuli evoked a response that was sensitive to synaptopathy, while being maximally insensitive to possible co-existing outer-hair-cell pathologies. We compared the model-predicted trends to AEPs recorded in younger and older listeners (N=44, 24f) who had normal or impaired audiograms with suspected age-related synaptopathy in the older cohort. We conclude that optimal stimulation paradigms for EFR-based quantification of synaptopathy should have sharply rising envelope shapes, a minimal plateau duration of 1.7-2.1 ms for a 120-Hz modulation rate, and inter-peak intervals which contain near-zero amplitudes. From our recordings, the optimal EFR-evoking stimulus had a rectangular envelope shape with a 25% duty cycle and a 95% modulation depth. Older listeners with normal or impaired audiometric thresholds showed significantly reduced EFRs, which were consistent with how (age-induced) synaptopathy affected these responses in the model.
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44
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Carcagno S, Plack CJ. Effects of age on psychophysical measures of auditory temporal processing and speech reception at low and high levels. Hear Res 2020; 400:108117. [PMID: 33253994 PMCID: PMC7812372 DOI: 10.1016/j.heares.2020.108117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 10/18/2020] [Accepted: 11/17/2020] [Indexed: 01/21/2023]
Abstract
We found little evidence of greater age-related hearing declines at high sound levels. There are age-related temporal-processing declines independent of hearing loss. No evidence of age-related speech-reception deficits independent of hearing loss.
Age-related cochlear synaptopathy (CS) has been shown to occur in rodents with minimal noise exposure, and has been hypothesized to play a crucial role in age-related hearing declines in humans. It is not known to what extent age-related CS occurs in humans, and how it affects the coding of supra-threshold sounds and speech in noise. Because in rodents CS affects mainly low- and medium-spontaneous rate (L/M-SR) auditory-nerve fibers with rate-level functions covering medium-high levels, it should lead to greater deficits in the processing of sounds at high than at low stimulus levels. In this cross-sectional study the performance of 102 listeners across the age range (34 young, 34 middle-aged, 34 older) was assessed in a set of psychophysical temporal processing and speech reception in noise tests at both low, and high stimulus levels. Mixed-effect multiple regression models were used to estimate the effects of age while partialing out effects of audiometric thresholds, lifetime noise exposure, cognitive abilities (assessed with additional tests), and musical experience. Age was independently associated with performance deficits on several tests. However, only for one out of 13 tests were age effects credibly larger at the high compared to the low stimulus level. Overall these results do not provide much evidence that age-related CS, to the extent to which it may occur in humans according to the rodent model of greater L/M-SR synaptic loss, has substantial effects on psychophysical measures of auditory temporal processing or on speech reception in noise.
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Affiliation(s)
- Samuele Carcagno
- Department of Psychology, Lancaster University, Lancaster, LA1 4YF, United Kingdom.
| | - Christopher J Plack
- Department of Psychology, Lancaster University, Lancaster, LA1 4YF, United Kingdom; Manchester Centre for Audiology and Deafness, University of Manchester, Academic Health Science Centre, M13 9PL, United Kingdom
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Krumbholz K, Hardy AJ, de Boer J. Automated extraction of auditory brainstem response latencies and amplitudes by means of non-linear curve registration. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 196:105595. [PMID: 32563894 PMCID: PMC7607223 DOI: 10.1016/j.cmpb.2020.105595] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 06/03/2020] [Indexed: 05/17/2023]
Abstract
BACKGROUND AND OBJECTIVES Animal results have suggested that auditory brainstem responses (ABRs) to transient sounds presented at supra-threshold levels may be useful for measuring hearing damage that is hidden to current audiometric tests. Evaluating such ABRs requires extracting the latencies and amplitudes of relevant deflections, or "waves". Currently, this is mostly done by human observers manually picking the waves' peaks and troughs in each individual response - a process that is both time-consuming and requiring of expert experience. Here, we propose a highly automated procedure for extracting individual ABR wave latencies and amplitudes based on the well-established methodology of non-linear curve registration. METHODS First, the to-be-analysed individual ABRs are temporally aligned - either with one another or, if available, with a pre-existing template - by locally compressing or stretching their time axes with smooth and invertible time warping functions. Then, the individual latencies and amplitudes of relevant ABR waves are obtained by picking the latencies of the waves' peaks and troughs on the common (aligned) time axis and combining these with the individual aligned responses and inverse time warping functions. RESULTS Using an example ABR data set with a wide range of response latencies and signal-to-noise ratios (SNRs), we test different choices for fitting the time warping functions. We cross-validate the warping results using independent response replicates and compare automatically and manually extracted latencies and amplitudes for ABR waves I and V. Using a Bayesian approach, we show that, for the best registration condition, automatic and manual data were statistically similar. CONCLUSIONS Non-linear curve registration can be used to temporally align individual ABRs and extract their wave latencies and amplitudes in a way that closely matches results from manual picking.
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Affiliation(s)
- Katrin Krumbholz
- School of Medicine, Hearing Sciences Group, University of Nottingham, United Kingdom.
| | - Alexander James Hardy
- School of Medicine, Hearing Sciences Group, University of Nottingham, United Kingdom; School of Psychology, University of Nottingham, United Kingdom
| | - Jessica de Boer
- School of Medicine, Hearing Sciences Group, University of Nottingham, United Kingdom
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Parker MA. Identifying three otopathologies in humans. Hear Res 2020; 398:108079. [PMID: 33011456 DOI: 10.1016/j.heares.2020.108079] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/25/2020] [Accepted: 09/16/2020] [Indexed: 01/19/2023]
Abstract
OBJECTIVES Hearing-in-noise (HIN) is a primary complaint of both the hearing impaired and the hearing aid user. Both auditory nerve (AN) function and outer hair cell (OHC) function are thought to contribute to HIN, but their relative contributions are still being elucidated. OHCs play a critical role in HIN by fine tuning the motion of the basilar membrane. Further, animal studies suggest that cochlear (auditory) synaptopathy, which is the loss of synaptic contact between hair cells and the AN, may be another cause of HIN difficulty. While there is evidence that cochlear synaptopathy occurs in animal models, there is debate as to whether cochlear synaptopathy is clinically significant in humans, which may be due to disparate methods of measuring noise exposure in humans and our high variability in susceptibility to noise damage. Rather than use self-reported noise exposure to define synaptopathic groups, this paper assumes that the general population exhibits a range of noise exposures and resulting otopathologies and defines cochlear synaptopathy "operationally" as low CAP amplitude accompanied by normal DPOAE levels in persons with low pure tone averages. The first question is whether the standard audiogram detects AN dysfunction and OHC dysfunction? The second question is whether HIN performance is primarily dependent on AN function, OHC function, or both functions? DESIGN Adult subjects have been recruited to participate in an ongoing study and variables such as age, self-reported gender, pure tone audiometry (0.25-20 kHz), subjective perception of HIN difficulty, Quick Speech-in Noise (QuickSIN) test, 45% time compressed word recognition (WR) in 10% reverberation and WR in the presence of ipsilateral speech-weighted noise have been collected. These variables were correlated with OHC function measured by distortion-product otoacoustic emission (DPOAE) signal to-noise-ratio (SNR), and AN function measured by compound action potential (CAP) peak amplitude and ratio to summating potential measured using electrocochleography. RESULTS Synaptopathy, by this operational definition, may be present in as many as 30% of individuals with normal hearing. Persons hearing within normal limits may exhibit HIN difficulties, and persons with hearing within normal limits may exhibit two distinct types of otopathologies undetected by the standard audiogram (a.k.a. hidden hearing loss) namely operational cochlear synaptopathy and OHC dysfunction. AN untuning secondary to OHC dysfunction is a third otopathology that occurs in subjects with a Mild-Moderate sensorineural hearing loss (SNHL). Clinical norms for each of these otopathologies are presented. Finally, the data show that operational cochlear synaptopathy does not correlate with HIN dysfunction. Rather, HIN performance is primarily governed by OHC function, while AN untuning also plays a lesser but statistically significant role. CONCLUSIONS The results of this study suggest the following: (1) persons hearing within normal limits may exhibit HIN difficulties; (2) persons hearing within normal limits may exhibit undetected otopathologies, namely AN dysfunction and OHC dysfunction; (3) AN untuning secondary to OHC dysfunction occurs in subjects with Mild-Moderate SNHL; (4) HIN performance is primarily governed by OHC function rather than AN function.
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Affiliation(s)
- Mark A Parker
- Department of Otolaryngology-Head and Neck Surgery, Steward St. Elizabeth's Medical Center, 736 Cambridge St., SMC-8, Brighton, MA 02135, United States; Tufts University School of Medicine, Boston MA, United States.
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47
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Carcagno S, Plack CJ. Effects of age on electrophysiological measures of cochlear synaptopathy in humans. Hear Res 2020; 396:108068. [PMID: 32979760 PMCID: PMC7593961 DOI: 10.1016/j.heares.2020.108068] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/11/2020] [Accepted: 08/31/2020] [Indexed: 12/19/2022]
Abstract
Age-related cochlear synaptopathy (CS) has been shown to occur in rodents with minimal noise exposure, and has been hypothesized to play a crucial role in age-related hearing declines in humans. Because CS affects mainly low-spontaneous rate auditory nerve fibers, differential electrophysiological measures such as the ratio of the amplitude of wave I of the auditory brainstem response (ABR) at high to low click levels (WIH/WIL), and the difference between frequency following response (FFR) levels to shallow and deep amplitude modulated tones (FFRS-FFRD), have been proposed as CS markers. However, age-related audiometric threshold shifts, particularly prominent at high frequencies, may confound the interpretation of these measures in cross-sectional studies of age-related CS. To address this issue, we measured WIH/WIL and FFRS-FFRD using highpass masking (HP) noise to eliminate the contribution of high-frequency cochlear regions to the responses in a cross-sectional sample of 102 subjects (34 young, 34 middle-aged, 34 older). WIH/WIL in the presence of the HP noise did not decrease as a function of age. However, in the absence of HP noise, WIH/WIL showed credible age-related decreases even after partialing out the effects of audiometric threshold shifts. No credible age-related decreases of FFRS-FFRD were found. Overall, the results do not provide evidence of age-related CS in the low-frequency region where the responses were restricted by the HP noise, but are consistent with the presence of age-related CS in higher frequency regions.
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Affiliation(s)
- Samuele Carcagno
- Department of Psychology, Lancaster University, Lancaster, LA1 4YF, United Kingdom.
| | - Christopher J Plack
- Department of Psychology, Lancaster University, Lancaster, LA1 4YF, United Kingdom; Manchester Centre for Audiology and Deafness, University of Manchester, Manchester Academic Health Science Centre, M13 9PL, United Kingdom
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Noise-Induced Hearing Loss and its Prevention: Current Issues in Mammalian Hearing. CURRENT OPINION IN PHYSIOLOGY 2020; 18:32-36. [PMID: 32984667 DOI: 10.1016/j.cophys.2020.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Noise-induced hearing loss (NIHL) has been well investigated across diverse mammalian species and the potential for prevention of NIHL is of broad interest. To most efficiently develop novel therapeutic interventions, a good understanding of the current state of knowledge regarding mechanisms of injury is essential. The overarching goals of this review are to 1) concisely summarize the current state of knowledge, and 2) provide opinions on the most significant future trends and developments.
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Brainstem correlates of cochlear nonlinearity measured via the scalp-recorded frequency-following response. Neuroreport 2020; 31:702-707. [PMID: 32453027 DOI: 10.1097/wnr.0000000000001452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The frequency-following response (FFR) is an EEG-based potential used to characterize the brainstem encoding of complex sounds. Adopting techniques from auditory signal processing, we assessed the degree to which FFRs encode important properties of cochlear processing (e.g. nonlinearities) and their relation to speech-in-noise (SIN) listening skills. Based on the premise that normal cochlear transduction is characterized by rectification and compression, we reasoned these nonlinearities would create measurable harmonic distortion in FFRs in response to even pure tone input. We recorded FFRs to nonspeech (pure- and amplitude-modulated-tones) stimuli in normal-hearing individuals. We then compared conventional indices of cochlear nonlinearity, via distortion product otoacoustic emission (DPOAE) I/O functions, to total harmonic distortion measured from neural FFRs (FFRTHD). Analysis of DPOAE growth and the FFRTHD revealed listeners with higher cochlear compression thresholds had lower neural FFRTHD distortion (i.e. more linear FFRs), thus linking cochlear and brainstem correlates of auditory nonlinearity. Importantly, FFRTHD was also negatively correlated with SIN perception whereby listeners with higher FFRTHD (i.e. more nonlinear responses) showed better performance on the QuickSIN. We infer individual differences in SIN perception and FFR nonlinearity even in normal-hearing individuals may reflect subtle differences in auditory health and suprathreshold hearing skills not captured by normal audiometric evaluation. Future studies in hearing-impaired individuals and animal models are necessary to confirm the diagnostic utility of FFRTHD and its relation to cochlear hearing loss or peripheral neurodegeneration in humans.
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Grant KJ, Mepani AM, Wu P, Hancock KE, de Gruttola V, Liberman MC, Maison SF. Electrophysiological markers of cochlear function correlate with hearing-in-noise performance among audiometrically normal subjects. J Neurophysiol 2020; 124:418-431. [PMID: 32639924 DOI: 10.1152/jn.00016.2020] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Hearing loss caused by noise exposure, ototoxic drugs, or aging results from the loss of sensory cells, as reflected in audiometric threshold elevation. Animal studies show that loss of hair cells can be preceded by loss of auditory-nerve peripheral synapses, which likely degrades auditory processing. While this condition, known as cochlear synaptopathy, can be diagnosed in mice by a reduction of suprathreshold cochlear neural responses, its diagnosis in humans remains challenging. To look for evidence of cochlear nerve damage in normal hearing subjects, we measured their word recognition performance in difficult listening environments and compared it to cochlear function as assessed by otoacoustic emissions and click-evoked electrocochleography. Several electrocochleographic markers were correlated with word scores, whereas distortion product otoacoustic emissions were not. Specifically, the summating potential (SP) was larger and the cochlear nerve action potential (AP) was smaller in those with the worst word scores. Adding a forward masker or increasing stimulus rate reduced SP in the worst performers, suggesting that this potential includes postsynaptic components as well as hair cell receptor potentials. Results suggests that some of the variance in word scores among listeners with normal audiometric threshold arises from cochlear neural damage.NEW & NOTEWORTHY Recent animal studies suggest that millions of people may be at risk of permanent impairment from cochlear synaptopathy, the age-related and noise-induced degeneration of neural connections in the inner ear that "hides" behind a normal audiogram. This study examines electrophysiological responses to clicks in a large cohort of subjects with normal hearing sensitivity. The resultant correlations with word recognition performance are consistent with an important contribution cochlear neural damage to deficits in hearing in noise abilities.
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Affiliation(s)
- Kelsie J Grant
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts
| | - Anita M Mepani
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts
| | - Peizhe Wu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts.,Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts
| | - Kenneth E Hancock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts.,Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts
| | - Victor de Gruttola
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts.,Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts.,Harvard Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts
| | - Stéphane F Maison
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, Massachusetts.,Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts.,Harvard Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, Massachusetts
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