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Prakash P, Sreedhar A, Umashankar A, Prabhu P. Effect of Contralateral Acoustic Stimulation on Temporal Processing Abilities in Individuals with Normal Hearing. Indian J Otolaryngol Head Neck Surg 2023; 75:685-691. [PMID: 37275046 PMCID: PMC10234946 DOI: 10.1007/s12070-022-03420-7] [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: 07/26/2021] [Accepted: 12/13/2022] [Indexed: 12/31/2022] Open
Abstract
The aim of the article was to compare the conditions of silent and contralateral noise on the temporal processing parameters. A total of 40 participants (20 males and 20 females) were enrolled in the study with a mean age of 21.7 years, participants with normal hearing thresholds and no history of middle ear pathology were enrolled for the study. The temporal processing tests such as duration discrimination test, gap detection test, and temporal modulation transfer function tests were carried out in these 40 individuals in the two conditions of silent and contralateral noise using MATLAB. Statistical analysis was carried out using the SPSS version 25.0 were descriptive and inferential statistics were carried out. Data was normally distributed on the Shapiro-Wilk's test of normality due to which a paired t test was carried out to establish the nature of significance between the silent and contralateral noise condition. Results reveal the presence of significant difference (p < 0.01) between the groups for all the parameters of temporal resolution with contralateral noise condition performing better than silent condition for the parameters. There is a positive effect of the efferent auditory pathway on the temporal resolution parameters thus implying that speech perception in noise is improved in the presence of background noise for normal hearing individuals due to this effect.
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Affiliation(s)
- Praveen Prakash
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
| | - Adithya Sreedhar
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
| | - Abishek Umashankar
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
| | - Prashanth Prabhu
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
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Lewis JD, Goettl-Meyer M, Lee D. Medial Olivocochlear Reflex Strength in Ears With Low-to-Moderate Annual Noise Exposure. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2023; 66:1428-1443. [PMID: 36940474 DOI: 10.1044/2022_jslhr-22-00433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
PURPOSE Studies in lower mammals demonstrate enhancement of the medial olivocochlear reflex (MOCR) following noise exposure. A similar effect may occur in humans, and there is some evidence of an individual's acoustic history affecting the MOCR. The current work evaluates the relationship between an individual's annual noise exposure history and their MOCR strength. Given the potential role of the MOCR as a biological hearing protector, it is important to identify factors associated with MOCR strength. METHOD Data were collected from 98 normal-hearing young adults. Annual noise exposure history was estimated using the Noise Exposure Questionnaire. MOCR strength was assayed using click-evoked otoacoustic emissions (CEOAEs) measured with and without noise presented to the contralateral ear. MOCR metrics included the MOCR-induced otoacoustic emission (OAE) magnitude shift and phase shift. A CEOAE signal-to-noise ratio (SNR) of at least 12 dB was required for estimation of the MOCR metrics. Linear regression was applied to evaluate the relationship between MOCR metrics and annual noise exposure. RESULTS Annual noise exposure was not a statistically significant predictor of the MOCR-induced CEOAE magnitude shift. However, annual noise exposure was a statistically significant predictor of the MOCR-induced CEOAE phase shift-the MOCR-induced phase shift decreased with increasing noise exposure. Additionally, annual noise exposure was a statistically significant predictor of OAE level. CONCLUSIONS Findings contrast with recent work that suggests MOCR strength increases with annual noise exposure. Compared with previous work, data for this study were collected using more stringent SNR criteria, which is expected to increase the precision of the MOCR metrics. Additionally, data were collected for a larger subject population with a wider range of noise exposures. Whether findings generalize to other exposure durations and levels is unknown and requires future study.
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Affiliation(s)
- James D Lewis
- Department of Audiology and Speech Pathology, The University of Tennessee Health Science Center, Knoxville
| | - Morgaine Goettl-Meyer
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora
| | - Donguk Lee
- Department of Audiology and Speech Pathology, The University of Tennessee Health Science Center, Knoxville
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Acuña F, Jeria R, Pavez E, Aguilar-Vidal E. Efferent Control in Musicians: A Review. Audiol Res 2023; 13:76-85. [PMID: 36648928 PMCID: PMC9844302 DOI: 10.3390/audiolres13010007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/30/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
It is widely established that musicians possess a higher level in certain auditory perceptual abilities when compared to non-musicians. This improvement may be mediated, at least in part, by changes in the cochlear response induced by reflex activation of the olivocochlear efferent system. In this review, we describe and analyze the scientific evidence regarding possible differences in the efferent response in musicians and non-musicians. The main evidence observed is that musicians present a greater robustness of the efferent olivocochlear reflex when measured by suppression of otoacoustic emissions and compared to non-musicians. Analyzing the articles presented in this review, it is possible to point out that the differential role of the efferent effect in musicians is not yet established. There is not enough evidence to support the idea that the olivocochlear system favors comparative changes in the properties of musicians' auditory filters. New studies with psychoacoustic techniques, among others, are needed to measure the effect of the olivocochlear reflex on tuning, gain, compression, or temporal resolution in musicians and non-musicians.
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Affiliation(s)
- Francisca Acuña
- Escuela de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Rodrigo Jeria
- Escuela de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Elisabeth Pavez
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
| | - Enzo Aguilar-Vidal
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
- Correspondence:
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Sreedhar A, Prakash P, Umashankar A, Prabhu P. Effect of Efferent Stimulation on the Differential Sensitivity in Individuals with Normal Hearing. Indian J Otolaryngol Head Neck Surg 2022; 74:4100-4105. [PMID: 36742897 PMCID: PMC9895606 DOI: 10.1007/s12070-021-02852-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: 06/14/2021] [Accepted: 09/02/2021] [Indexed: 02/07/2023] Open
Abstract
The aim of the article was to compare the conditions of silent and contralateral noise on Differential sensitivity in normal hearing individuals. A total of 40 participants (20 males and 20 females) were enrolled in the study with a mean age of 21.7 years, participants with normal hearing thresholds and no history of middle ear pathology were enrolled for the study. Difference limen tests such as difference limen for intensity (DLI), difference limen for frequency (DLF), and difference limen for time (DLT) were carried out in these 40 individuals in the two conditions of silent and contralateral noise using MATLAB. Statistical analysis was carried out using the SPSS version 25.0 were descriptive and inferential statistics were carried out. Data was normally distributed on the Shapiro-Wilk's test of normality due to which a paired t test was carried out to establish the nature of significance between the silent and contralateral noise condition. Results reveal the presence of significant difference (P < 0.01) between the groups for DLF and DLT with contralateral noise condition performing better than silent condition for the parameters. However, no significant difference was obtained for DLI. There is a positive effect of the efferent auditory pathway on the Differential sensitivity thus implying that speech perception in noise is improved in the presence of background noise for normal hearing individuals due to this effect. But in case of DLI, the reduced spread of excitation could be the reason why there were no significant differences between silent and contralateral noise condition.
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Affiliation(s)
- Adithya Sreedhar
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
| | - Praveen Prakash
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
| | - Abishek Umashankar
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
| | - Prashanth Prabhu
- Department of Audiology, All India Institute of Speech and Hearing Mysuru, Naimisham Campus, Road No. 3 TK Layout, Manasagangotri, Mysuru, Karnataka 570006 India
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Miranda FA, Aguilar-Vidal E. Magnitude of the contralateral efferent olivocochlear effect as a function of the frequency. J Otol 2022; 17:67-71. [PMID: 35949552 PMCID: PMC9349011 DOI: 10.1016/j.joto.2021.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/07/2021] [Accepted: 11/30/2021] [Indexed: 11/28/2022] Open
Abstract
Background The activation of the medial olivocochlear reflex reduces the cochlear gain, which is manifested perceptually as decreased auditory sensitivity. However, it has remained unclear whether the extent of this suppression varies according to the cochlear region involved. Here we aims to assess the magnitude of contralateral efferent suppression across human cochlea, at low levels, and its impact on hearing sensitivity. Methods Assuming that acoustic stimulation activates the contralateral medial olivocochlear reflex, we evaluated the magnitude of the suppressive effect as a function of frequency in 17 subjects with normal hearing. Absolute thresholds were measured for bursts tones of various durations (10, 100, and 500 ms) and frequencies (250, 500, 1000, 4000, and 8000 Hz) in the presence or absence of contralateral white noise at 60 dB SPL. Results We found that contralateral noise raised the absolute threshold for the burst tones evaluated. The effect was greater at lower than higher frequencies (3.85 dB at 250 Hz vs. 2.22 dB at 8000 Hz). Conclusions Our findings suggest that in humans, the magnitude of this suppression varies according to the cochlear region stimulated, with a greater effect towards the apex (lower frequencies) than the base (higher frequencies) of the cochlea.
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Affiliation(s)
- Fernanda Anza Miranda
- Laboratorio de Audiología y Percepción Auditiva, Facultad de Medicina, Universidad de Chile, Chile
- Escuela de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Chile
| | - Enzo Aguilar-Vidal
- Laboratorio de Audiología y Percepción Auditiva, Facultad de Medicina, Universidad de Chile, Chile
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Chile
- Corresponding author. Independencia 1027, Departamento Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, 9786060 Chile.
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Salloom WB, Strickland EA. The effect of broadband elicitor laterality on psychoacoustic gain reduction across signal frequency. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:2817. [PMID: 34717476 PMCID: PMC8520488 DOI: 10.1121/10.0006662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 09/17/2021] [Accepted: 09/21/2021] [Indexed: 05/19/2023]
Abstract
There are psychoacoustic methods thought to measure gain reduction, which may be from the medial olivocochlear reflex (MOCR), a bilateral feedback loop that adjusts cochlear gain. Although studies have used ipsilateral and contralateral elicitors and have examined strength at different signal frequencies, these factors have not been examined within a single study. Therefore, basic questions about gain reduction, such as the relative strength of ipsilateral vs contralateral elicitation and the relative strength across signal frequency, are not known. In the current study, gain reduction from ipsilateral, contralateral, and bilateral elicitors was measured at 1-, 2-, and 4-kHz signal frequencies using forward masking paradigms at a range of elicitor levels in a repeated measures design. Ipsilateral and bilateral strengths were similar and significantly larger than contralateral strength across signal frequencies. Growth of gain reduction with precursor level tended to differ with signal frequency, although not significantly. Data from previous studies are considered in light of the results of this study. Behavioral results are also considered relative to anatomical and physiological data on the MOCR. These results indicate that, in humans, cochlear gain reduction is broad across frequencies and is robust for ipsilateral and bilateral elicitation but small for contralateral elicitation.
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Affiliation(s)
- William B Salloom
- Department of Speech, Language, and Hearing Sciences, Purdue University, 715 Clinic Drive, West Lafayette, Indiana 47907, USA
| | - Elizabeth A Strickland
- Department of Speech, Language, and Hearing Sciences, Purdue University, 715 Clinic Drive, West Lafayette, Indiana 47907, USA
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Jedrzejczak WW, Pilka E, Kochanek K, Skarzynski H. Does the Presence of Spontaneous Components Affect the Reliability of Contralateral Suppression of Evoked Otoacoustic Emissions? Ear Hear 2021; 42:990-1005. [PMID: 33480622 DOI: 10.1097/aud.0000000000000996] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The function of the medial olivocochlear system can be evaluated by measuring the suppression of otoacoustic emissions (OAEs) by contralateral stimulation. One of the obstacles preventing the clinical use of the OAE suppression is that it has considerable variability across subjects. One feature that tends to differentiate subjects is the presence or absence of spontaneous OAEs (SOAEs). The purpose of the present study was to investigate the reliability of contralateral suppression of transiently evoked OAEs (TEOAEs) measured using a commercial device in ears with and without SOAEs. DESIGN OAEs were recorded in a group of 60 women with normal hearing. TEOAEs were recorded with a linear protocol (identical stimuli), a constant stimulus level of 65 dB peSPL, and contralateral broadband noise (60 dB SPL) as a suppressor. Each recording session consisted of three measurements: the first two were made consecutively without taking out the probe (the "no refit" condition); the third measurement was made after taking out and refitting the probe (a "refit" condition). Global (for the whole signal) and half-octave band values of TEOAE response levels, signal-to-noise ratios (SNRs), raw dB TEOAE suppression, and normalized TEOAE suppression, and latency were investigated. Each subject was tested for the presence of SOAEs using the synchronized SOAE (SSOAE) technique. Reliability was evaluated by calculating the intraclass correlation coefficient, standard error of measurement (SEM) and minimum detectable change. RESULTS The TEOAE suppression was higher in ears with SSOAEs in terms of normalized percentages. However, when calculated in terms of decibels, the effect was not significant. The reliability of the TEOAE suppression as assessed by SEM was similar for ears with and without SSOAEs. The SEM for the whole dataset (with and without SSOAEs) was 0.08 dB for the no-refit condition and 0.13 dB for the refit condition (equivalent to 1.6% and 2.2%, respectively). SEMs were higher for half-octave bands than for global values. TEOAE SNRs were higher in ears with SSOAEs. CONCLUSIONS The effect of SSOAEs on reliability of the TEOAE suppression remains complicated. On the one hand, we found that higher SNRs generally provide lower variability of calculated suppressions, and that the presence of SSOAEs favors high SNRs. On the other hand, reliability estimates were not much different between ears with and without SSOAEs. Therefore, in a clinical setting, the presence of SOAEs does not seem to have an effect on suppression measures, at least when testing involves measuring global or half-octave band response levels.
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Affiliation(s)
- W Wiktor Jedrzejczak
- Institute of Physiology and Pathology of Hearing, Warsaw, Poland.,World Hearing Center, Kajetany, Nadarzyn, Poland
| | - Edyta Pilka
- Institute of Physiology and Pathology of Hearing, Warsaw, Poland.,World Hearing Center, Kajetany, Nadarzyn, Poland
| | - Krzysztof Kochanek
- Institute of Physiology and Pathology of Hearing, Warsaw, Poland.,World Hearing Center, Kajetany, Nadarzyn, Poland
| | - Henryk Skarzynski
- Institute of Physiology and Pathology of Hearing, Warsaw, Poland.,World Hearing Center, Kajetany, Nadarzyn, Poland
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Lopez-Poveda EA, Eustaquio-Martín A, Fumero MJ, Gorospe JM, Polo López R, Gutiérrez Revilla MA, Schatzer R, Nopp P, Stohl JS. Speech-in-Noise Recognition With More Realistic Implementations of a Binaural Cochlear-Implant Sound Coding Strategy Inspired by the Medial Olivocochlear Reflex. Ear Hear 2021; 41:1492-1510. [PMID: 33136626 PMCID: PMC7722463 DOI: 10.1097/aud.0000000000000880] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 03/24/2020] [Indexed: 12/15/2022]
Abstract
OBJECTIVES Cochlear implant (CI) users continue to struggle understanding speech in noisy environments with current clinical devices. We have previously shown that this outcome can be improved by using binaural sound processors inspired by the medial olivocochlear (MOC) reflex, which involve dynamic (contralaterally controlled) rather than fixed compressive acoustic-to-electric maps. The present study aimed at investigating the potential additional benefits of using more realistic implementations of MOC processing. DESIGN Eight users of bilateral CIs and two users of unilateral CIs participated in the study. Speech reception thresholds (SRTs) for sentences in competition with steady state noise were measured in unilateral and bilateral listening modes. Stimuli were processed through two independently functioning sound processors (one per ear) with fixed compression, the current clinical standard (STD); the originally proposed MOC strategy with fast contralateral control of compression (MOC1); a MOC strategy with slower control of compression (MOC2); and a slower MOC strategy with comparatively greater contralateral inhibition in the lower-frequency than in the higher-frequency channels (MOC3). Performance with the four strategies was compared for multiple simulated spatial configurations of the speech and noise sources. Based on a previously published technical evaluation of these strategies, we hypothesized that SRTs would be overall better (lower) with the MOC3 strategy than with any of the other tested strategies. In addition, we hypothesized that the MOC3 strategy would be advantageous over the STD strategy in listening conditions and spatial configurations where the MOC1 strategy was not. RESULTS In unilateral listening and when the implant ear had the worse acoustic signal-to-noise ratio, the mean SRT was 4 dB worse for the MOC1 than for the STD strategy (as expected), but it became equal or better for the MOC2 or MOC3 strategies than for the STD strategy. In bilateral listening, mean SRTs were 1.6 dB better for the MOC3 strategy than for the STD strategy across all spatial configurations tested, including a condition with speech and noise sources colocated at front where the MOC1 strategy was slightly disadvantageous relative to the STD strategy. All strategies produced significantly better SRTs for spatially separated than for colocated speech and noise sources. A statistically significant binaural advantage (i.e., better mean SRTs across spatial configurations and participants in bilateral than in unilateral listening) was found for the MOC2 and MOC3 strategies but not for the STD or MOC1 strategies. CONCLUSIONS Overall, performance was best with the MOC3 strategy, which maintained the benefits of the originally proposed MOC1 strategy over the STD strategy for spatially separated speech and noise sources and extended those benefits to additional spatial configurations. In addition, the MOC3 strategy provided a significant binaural advantage, which did not occur with the STD or the original MOC1 strategies.
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Affiliation(s)
- Enrique A. Lopez-Poveda
- Laboratorio de Audición Computacional y Psicoacústica, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
- Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - Almudena Eustaquio-Martín
- Laboratorio de Audición Computacional y Psicoacústica, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Milagros J. Fumero
- Laboratorio de Audición Computacional y Psicoacústica, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - José M. Gorospe
- Laboratorio de Audición Computacional y Psicoacústica, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain
- Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
- Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, Salamanca, Spain
- Unidad de Foniatría, Logopedia y Audiología, Servicio de Otorrinolaringología, Hospital Universitario de Salamanca, Salamanca, Spain
| | - Rubén Polo López
- Servicio de Otorrinolaringología, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | | | | | | | - Joshua S. Stohl
- North American Research Laboratory, MED-EL Corporation, Durham, North Carolina, USA
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Jennings SG. The role of the medial olivocochlear reflex in psychophysical masking and intensity resolution in humans: a review. J Neurophysiol 2021; 125:2279-2308. [PMID: 33909513 PMCID: PMC8285664 DOI: 10.1152/jn.00672.2020] [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: 12/01/2020] [Revised: 03/16/2021] [Accepted: 04/02/2021] [Indexed: 02/01/2023] Open
Abstract
This review addresses the putative role of the medial olivocochlear (MOC) reflex in psychophysical masking and intensity resolution in humans. A framework for interpreting psychophysical results in terms of the expected influence of the MOC reflex is introduced. This framework is used to review the effects of a precursor or contralateral acoustic stimulation on 1) simultaneous masking of brief tones, 2) behavioral estimates of cochlear gain and frequency resolution in forward masking, 3) the buildup and decay of forward masking, and 4) measures of intensity resolution. Support, or lack thereof, for a role of the MOC reflex in psychophysical perception is discussed in terms of studies on estimates of MOC strength from otoacoustic emissions and the effects of resection of the olivocochlear bundle in patients with vestibular neurectomy. Novel, innovative approaches are needed to resolve the dissatisfying conclusion that current results are unable to definitively confirm or refute the role of the MOC reflex in masking and intensity resolution.
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Affiliation(s)
- Skyler G Jennings
- Department of Communication Sciences and Disorders, The University of Utah, Salt Lake City, Utah
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10
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Marrufo-Pérez MI, Johannesen PT, Lopez-Poveda EA. Correlation and Reliability of Behavioral and Otoacoustic-Emission Estimates of Contralateral Medial Olivocochlear Reflex Strength in Humans. Front Neurosci 2021; 15:640127. [PMID: 33664649 PMCID: PMC7921326 DOI: 10.3389/fnins.2021.640127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 01/26/2021] [Indexed: 11/18/2022] Open
Abstract
The roles of the medial olivocochlear reflex (MOCR) in human hearing have been widely investigated but remain controversial. We reason that this may be because the effects of MOCR activation on cochlear mechanical responses can be assessed only indirectly in healthy humans, and the different methods used to assess those effects possibly yield different and/or unreliable estimates. One aim of this study was to investigate the correlation between three methods often employed to assess the strength of MOCR activation by contralateral acoustic stimulation (CAS). We measured tone detection thresholds (N = 28), click-evoked otoacoustic emission (CEOAE) input/output (I/O) curves (N = 18), and distortion-product otoacoustic emission (DPOAE) I/O curves (N = 18) for various test frequencies in the presence and the absence of CAS (broadband noise of 60 dB SPL). As expected, CAS worsened tone detection thresholds, suppressed CEOAEs and DPOAEs, and horizontally shifted CEOAE and DPOAE I/O curves to higher levels. However, the CAS effect on tone detection thresholds was not correlated with the horizontal shift of CEOAE or DPOAE I/O curves, and the CAS-induced CEOAE suppression was not correlated with DPOAE suppression. Only the horizontal shifts of CEOAE and DPOAE I/O functions were correlated with each other at 1.5, 2, and 3 kHz. A second aim was to investigate which of the methods is more reliable. The test–retest variability of the CAS effect was high overall but smallest for tone detection thresholds and CEOAEs, suggesting that their use should be prioritized over the use of DPOAEs. Many factors not related with the MOCR, including the limited parametric space studied, the low resolution of the I/O curves, and the reduced numbers of observations due to data exclusion likely contributed to the weak correlations and the large test–retest variability noted. These findings can help us understand the inconsistencies among past studies and improve our understanding of the functional significance of the MOCR.
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Affiliation(s)
- Miriam I Marrufo-Pérez
- 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
| | - 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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11
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Liu Y, Xu R, Gong Q. Human Auditory-Frequency Tuning Is Sensitive to Tonal Language Experience. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2020; 63:4277-4288. [PMID: 33151817 DOI: 10.1044/2020_jslhr-20-00152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Purpose The aim of this study is to investigate whether human auditory frequency tuning can be influenced by tonal language experience. Method Perceptual tuning measured via psychophysical tuning curves and cochlear tuning derived via stimulus-frequency otoacoustic emission suppression tuning curves in 14 native speakers of a tonal language (Mandarin) were compared to those of 14 native speakers of a nontonal language (English) at 1 and 4 kHz. Results Group comparisons of both psychophysical tuning curves (p = .046) and stimulus-frequency otoacoustic emission suppression tuning curves (p = .007) in the 4-kHz region indicated sharper frequency tuning in the Mandarin-speaking group relative to the English-speaking group. The auditory tuning was better at the higher (4 kHz) than the lower (1 kHz) probe frequencies (p < .001). Conclusions The sharper auditory tuning in the 4-kHz cochlear region is associated with long-term tonal language (i.e., Mandarin) experience. Experience-dependent plasticity of tonal language may occur before the sound signal reaches central neural stages, as peripheral as the cochlea.
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Affiliation(s)
- Yin Liu
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Runyi Xu
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
| | - Qin Gong
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China
- School of Medicine, Shanghai University, China
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12
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Jedrzejczak WW, Milner R, Ganc M, Pilka E, Skarzynski H. No Change in Medial Olivocochlear Efferent Activity during an Auditory or Visual Task: Dual Evidence from Otoacoustic Emissions and Event-Related Potentials. Brain Sci 2020; 10:E894. [PMID: 33238438 PMCID: PMC7700184 DOI: 10.3390/brainsci10110894] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/17/2020] [Accepted: 11/21/2020] [Indexed: 11/17/2022] Open
Abstract
The medial olivocochlear (MOC) system is thought to be responsible for modulation of peripheral hearing through descending (efferent) pathways. This study investigated the connection between peripheral hearing function and conscious attention during two different modality tasks, auditory and visual. Peripheral hearing function was evaluated by analyzing the amount of suppression of otoacoustic emissions (OAEs) by contralateral acoustic stimulation (CAS), a well-known effect of the MOC. Simultaneously, attention was evaluated by event-related potentials (ERPs). Although the ERPs showed clear differences in processing of auditory and visual tasks, there were no differences in the levels of OAE suppression. We also analyzed OAEs for the highest magnitude resonant mode signal detected by the matching pursuit method, but again did not find a significant effect of task, and no difference in noise level or number of rejected trials. However, for auditory tasks, the amplitude of the P3 cognitive wave negatively correlated with the level of OAE suppression. We conclude that there seems to be no change in MOC function when performing different modality tasks, although the cortex still remains able to modulate some aspects of MOC activity.
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Affiliation(s)
- W. Wiktor Jedrzejczak
- Institute of Physiology and Pathology of Hearing, ul. M. Mochnackiego 10, 02-042 Warsaw, Poland; (R.M.); (M.G.); (E.P.); (H.S.)
- World Hearing Center, ul. Mokra 17, 05-830 Nadarzyn, Poland
| | - Rafal Milner
- Institute of Physiology and Pathology of Hearing, ul. M. Mochnackiego 10, 02-042 Warsaw, Poland; (R.M.); (M.G.); (E.P.); (H.S.)
- World Hearing Center, ul. Mokra 17, 05-830 Nadarzyn, Poland
| | - Malgorzata Ganc
- Institute of Physiology and Pathology of Hearing, ul. M. Mochnackiego 10, 02-042 Warsaw, Poland; (R.M.); (M.G.); (E.P.); (H.S.)
- World Hearing Center, ul. Mokra 17, 05-830 Nadarzyn, Poland
| | - Edyta Pilka
- Institute of Physiology and Pathology of Hearing, ul. M. Mochnackiego 10, 02-042 Warsaw, Poland; (R.M.); (M.G.); (E.P.); (H.S.)
- World Hearing Center, ul. Mokra 17, 05-830 Nadarzyn, Poland
| | - Henryk Skarzynski
- Institute of Physiology and Pathology of Hearing, ul. M. Mochnackiego 10, 02-042 Warsaw, Poland; (R.M.); (M.G.); (E.P.); (H.S.)
- World Hearing Center, ul. Mokra 17, 05-830 Nadarzyn, Poland
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13
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Tarnowska E, Wicher A, Moore BCJ. No Influence of Musicianship on the Effect of Contralateral Stimulation on Frequency Selectivity. Trends Hear 2020; 24:2331216520939776. [PMID: 32840175 PMCID: PMC7450455 DOI: 10.1177/2331216520939776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The efferent system may control the gain of the cochlea and thereby
influence frequency selectivity. This effect can be assessed using
contralateral stimulation (CS) applied to the ear opposite to that
used to assess frequency selectivity. The effect of CS may be stronger
for musicians than for nonmusicians. To assess whether this was the
case, psychophysical tuning curves (PTCs) were compared for 12
musicians and 12 nonmusicians. The PTCs were measured with and without
a 60-dB sound pressure level (SPL) pink-noise CS, using signal
frequencies of 2 and 4 kHz. The sharpness of the PTCs was quantified
using the measure Q10, the signal frequency divided by the PTC
bandwidth measured 10 dB above the level at the tip. Q10 values were
lower in the presence of the CS, but this effect did not differ
significantly for musicians and nonmusicians. The main effect of group
(musicians vs. nonmusicians) on the Q10 values was not significant.
Overall, these results do not support the idea that musicianship
enhances contralateral efferent gain control as measured using the
effect of CS on PTCs.
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Affiliation(s)
- Emilia Tarnowska
- Chair of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland
| | - Andrzej Wicher
- Chair of Acoustics, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland
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Lopez-Poveda EA, Eustaquio-Martín A, Fumero MJ, Stohl JS, Schatzer R, Nopp P, Wolford RD, Gorospe JM, Polo R, Revilla AG, Wilson BS. Lateralization of virtual sound sources with a binaural cochlear-implant sound coding strategy inspired by the medial olivocochlear reflex. Hear Res 2019; 379:103-116. [DOI: 10.1016/j.heares.2019.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 04/30/2019] [Accepted: 05/17/2019] [Indexed: 10/26/2022]
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15
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Mattsson TS, Lind O, Follestad T, Grøndahl K, Wilson W, Nordgård S. Contralateral suppression of otoacoustic emissions in a clinical sample of children with auditory processing disorder. Int J Audiol 2019; 58:301-310. [DOI: 10.1080/14992027.2019.1570358] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Tone Stokkereit Mattsson
- Department of Otorhinolaryngology, Head and Neck Surgery, Ålesund Hospital, Ålesund, Norway
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ola Lind
- Department of Otorhinolaryngology, Head and Neck Surgery, Haukeland University Hospital, Bergen, Norway
| | - Turid Follestad
- Department of Public Health and General Practice, Norwegian University of Science and Technology, Trondheim, Norway
| | - Kjell Grøndahl
- Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway
| | - Wayne Wilson
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia
| | - Ståle Nordgård
- Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Otorhinolaryngology, Head and Neck Surgery, St. Olavs University Hospital, Trondheim, Norway
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16
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Nogueira W, Krüger B, Büchner A, Lopez-Poveda E. Contralateral suppression of human hearing sensitivity in single-sided deaf cochlear implant users. Hear Res 2018; 373:121-129. [PMID: 29941311 DOI: 10.1016/j.heares.2018.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 05/28/2018] [Accepted: 06/07/2018] [Indexed: 11/16/2022]
Abstract
Cochlear implants (CIs) are being implanted in people with unilateral hearing loss because they can improve speech intelligibility and sound source localization. Though designed to restore the afferent auditory stimulation, the CI possibly restores some efferent effects. The present study aimed at investigating this possibility. Five single-sided deaf CI users with less than 30 dB hearing loss up to 4 kHz in their acoustic ear participated in the study. Absolute thresholds for their acoustic ears were measured for pure tones of 500 and 4000 Hz with durations of 10 and 200 ms in the presence and in the absence of contralateral broadband electrical stimulation (CBES) delivered with the CI. The electrical stimulus consisted of pulse trains (symmetric biphasic pulses with phase duration 36 μs) on all 16 electrodes sequentially stimulated at a rate of 843 Hz. Its intensity was set to sound as loud as broadband noise at 50 or 60 dB SPL in the acoustic ear. Thresholds were measured using a three-interval, three-alternative, forced-choice procedure with a two-down, one-up adaptive rule to estimate the level for 71% correct in the psychometric function. Thresholds measured without the CBES were lower for the longer than for the shorter tones, and the difference was larger at 500 than at 4000 Hz. CBES equivalent to 50 or 60 dB SPL caused significant threshold elevation only for short (10 ms) and low frequency (500 Hz) acoustic tones of 1.2 and 2.2 dB. These increases appear smaller than previously reported for normal hearing listeners in related experiments. These results support the notion that for single-sided deaf CI users, the CI modulates hearing in the acoustic ear. The possible mechanisms that may be contributing this effect are discussed.
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Affiliation(s)
- Waldo Nogueira
- Medical University Hannover, Cluster of Excellence "Hearing4all", Hannover, Germany.
| | - Benjamin Krüger
- Medical University Hannover, Cluster of Excellence "Hearing4all", Hannover, Germany
| | - Andreas Büchner
- Medical University Hannover, Cluster of Excellence "Hearing4all", Hannover, Germany
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17
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DeRoy Milvae K, Strickland EA. Psychoacoustic measurements of ipsilateral cochlear gain reduction as a function of signal frequency. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:3114. [PMID: 29857720 PMCID: PMC5967972 DOI: 10.1121/1.5038254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 03/09/2018] [Accepted: 04/30/2018] [Indexed: 05/19/2023]
Abstract
Forward masking experiments at 4 kHz have demonstrated that preceding sound can elicit changes in masking patterns consistent with a change in cochlear gain. However, the acoustic environment is filled with complex sounds, often dominated by lower frequencies, and ipsilateral cochlear gain reduction at frequencies below 4 kHz is largely unstudied in the forward masking literature. In this experiment, the magnitude of ipsilateral cochlear gain reduction was explored at 1, 2, and 4 kHz using forward masking techniques in an effort to evaluate a range of frequencies in listeners with normal hearing. Gain reduction estimates were not significantly different at 2 and 4 kHz using two forward masking measurements. Although the frequency was a significant factor in the analysis, post hoc testing supported the interpretation that gain reduction estimates measured without a masker were not significantly different at 1, 2, and 4 kHz. A second experiment provided evidence that forward masking in this paradigm at 1 kHz cannot be explained by excitation alone. This study provides evidence of ipsilateral cochlear gain reduction in humans at frequencies below the 4 kHz region.
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Affiliation(s)
- Kristina DeRoy Milvae
- Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana 47907, USA
| | - Elizabeth A Strickland
- Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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18
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Marrufo-Pérez MI, Eustaquio-Martín A, Lopez-Poveda EA. Adaptation to Noise in Human Speech Recognition Unrelated to the Medial Olivocochlear Reflex. J Neurosci 2018; 38:4138-4145. [PMID: 29593051 PMCID: PMC6596031 DOI: 10.1523/jneurosci.0024-18.2018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 02/26/2018] [Accepted: 03/24/2018] [Indexed: 11/21/2022] Open
Abstract
Sensory systems constantly adapt their responses to the current environment. In hearing, adaptation may facilitate communication in noisy settings, a benefit frequently (but controversially) attributed to the medial olivocochlear reflex (MOCR) enhancing the neural representation of speech. Here, we show that human listeners (N = 14; five male) recognize more words presented monaurally in ipsilateral, contralateral, and bilateral noise when they are given some time to adapt to the noise. This finding challenges models and theories that claim that speech intelligibility in noise is invariant over time. In addition, we show that this adaptation to the noise occurs also for words processed to maintain the slow-amplitude modulations in speech (the envelope) disregarding the faster fluctuations (the temporal fine structure). This demonstrates that noise adaptation reflects an enhancement of amplitude modulation speech cues and is unaffected by temporal fine structure cues. Last, we show that cochlear implant users (N = 7; four male) show normal monaural adaptation to ipsilateral noise. Because the electrical stimulation delivered by cochlear implants is independent from the MOCR, this demonstrates that noise adaptation does not require the MOCR. We argue that noise adaptation probably reflects adaptation of the dynamic range of auditory neurons to the noise level statistics.SIGNIFICANCE STATEMENT People find it easier to understand speech in noisy environments when they are given some time to adapt to the noise. This benefit is frequently but controversially attributed to the medial olivocochlear efferent reflex enhancing the representation of speech cues in the auditory nerve. Here, we show that the adaptation to noise reflects an enhancement of the slow fluctuations in amplitude over time that are present in speech. In addition, we show that adaptation to noise for cochlear implant users is not statistically different from that for listeners with normal hearing. Because the electrical stimulation delivered by cochlear implants is independent from the medial olivocochlear efferent reflex, this demonstrates that adaptation to noise does not require this reflex.
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Affiliation(s)
- Miriam I Marrufo-Pérez
- Instituto de Neurociencias de Castilla y León
- Instituto de Investigación Biomédica de Salamanca, and
| | | | - Enrique A Lopez-Poveda
- Instituto de Neurociencias de Castilla y León,
- Instituto de Investigación Biomédica de Salamanca, and
- Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, 37007 Salamanca, Spain
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Frequency specificity and left-ear advantage of medial olivocochlear efferent modulation: a study based on stimulus frequency otoacoustic emission. Neuroreport 2018; 28:775-778. [PMID: 28538522 DOI: 10.1097/wnr.0000000000000812] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The medial olivocochlear (MOC) bundle is an auditory nucleus that projects efferent nerve fibers to the outer hair cells (OHCs) for synaptic innervation. The aim of the present study was to investigate the possible existence of frequency and ear specificity in MOC efferent modulation, as well as how MOC activation influences cochlear tuning. Stimulus frequency otoacoustic emissions (SFOAEs) were used to study MOC efferent modulation. Therefore, the current experiment was designed to compare the degree of SFOAE suppression in the both ears of 20 individuals at 1, 2, 4, and 8 kHz. We also compared changes in Q10 values of SFOAE suppression tuning curves at 1, 2, and 4 kHz under contralateral acoustic stimulation (CAS) and no-CAS conditions. We observed a significant reduction in SFOAE magnitude in the CAS condition compared with the no-CAS condition at 1 and 2 kHz in the left ear. A significant difference in CAS suppression was also found between the left and right ears at 1 and 2 kHz, with larger CAS suppression in the left ear. CAS further produced a statistically significant increase in the Q10 value at 1 kHz and a significant reduction in Q10 values at 2 and 4 kHz. These findings suggest a left-ear advantage in terms of CAS-induced MOC efferent SFOAE suppression, with larger MOC efferent modulation for lower frequencies, and cochlear tuning was sharpened by means of MOC activation at lower frequencies and broadened at higher frequencies.
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20
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Lopez-Poveda EA, Eustaquio-Martín A. Objective speech transmission improvements with a binaural cochlear implant sound-coding strategy inspired by the contralateral medial olivocochlear reflex. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:2217. [PMID: 29716283 DOI: 10.1121/1.5031028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
It has been recently shown that cochlear implant users could enjoy better speech reception in noise and enhanced spatial unmasking with binaural audio processing inspired by the inhibitory effects of the contralateral medial olivocochlear (MOC) reflex on compression [Lopez-Poveda, Eustaquio-Martin, Stohl, Wolford, Schatzer, and Wilson (2016). Ear Hear. 37, e138-e148]. The perceptual evidence supporting those benefits, however, is limited to a few target-interferer spatial configurations and to a particular implementation of contralateral MOC inhibition. Here, the short-term objective intelligibility index is used to (1) objectively demonstrate potential benefits over many more spatial configurations, and (2) investigate if the predicted benefits may be enhanced by using more realistic MOC implementations. Results corroborate the advantages and drawbacks of MOC processing indicated by the previously published perceptual tests. The results also suggest that the benefits may be enhanced and the drawbacks overcome by using longer time constants for the activation and deactivation of inhibition and, to a lesser extent, by using a comparatively greater inhibition in the lower than in the higher frequency channels. Compared to using two functionally independent processors, the better MOC processor improved the signal-to-noise ratio in the two ears between 1 and 6 decibels by enhancing head-shadow effects, and was advantageous for all tested target-interferer spatial configurations.
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Affiliation(s)
- Enrique A Lopez-Poveda
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Calle Pintor Fernando Gallego 1, Salamanca 37007, Spain
| | - Almudena Eustaquio-Martín
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Calle Pintor Fernando Gallego 1, Salamanca 37007, Spain
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21
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Lopez-Poveda EA. Olivocochlear Efferents in Animals and Humans: From Anatomy to Clinical Relevance. Front Neurol 2018; 9:197. [PMID: 29632514 PMCID: PMC5879449 DOI: 10.3389/fneur.2018.00197] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/13/2018] [Indexed: 11/13/2022] Open
Abstract
Olivocochlear efferents allow the central auditory system to adjust the functioning of the inner ear during active and passive listening. While many aspects of efferent anatomy, physiology and function are well established, others remain controversial. This article reviews the current knowledge on olivocochlear efferents, with emphasis on human medial efferents. The review covers (1) the anatomy and physiology of olivocochlear efferents in animals; (2) the methods used for investigating this auditory feedback system in humans, their limitations and best practices; (3) the characteristics of medial-olivocochlear efferents in humans, with a critical analysis of some discrepancies across human studies and between animal and human studies; (4) the possible roles of olivocochlear efferents in hearing, discussing the evidence in favor and against their role in facilitating the detection of signals in noise and in protecting the auditory system from excessive acoustic stimulation; and (5) the emerging association between abnormal olivocochlear efferent function and several health conditions. Finally, we summarize some open issues and introduce promising approaches for investigating the roles of efferents in human hearing using cochlear implants.
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Affiliation(s)
- Enrique A Lopez-Poveda
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain.,Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
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22
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Marrufo-Pérez MI, Eustaquio-Martín A, López-Bascuas LE, Lopez-Poveda EA. Temporal Effects on Monaural Amplitude-Modulation Sensitivity in Ipsilateral, Contralateral and Bilateral Noise. J Assoc Res Otolaryngol 2018; 19:147-161. [PMID: 29508100 DOI: 10.1007/s10162-018-0656-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 02/05/2018] [Indexed: 10/17/2022] Open
Abstract
The amplitude modulations (AMs) in speech signals are useful cues for speech recognition. Several adaptation mechanisms may make the detection of AM in noisy backgrounds easier when the AM carrier is presented later rather than earlier in the noise. The aim of the present study was to characterize temporal adaptation to noise in AM detection. AM detection thresholds were measured for monaural (50 ms, 1.5 kHz) pure-tone carriers presented at the onset ('early' condition) and 300 ms after the onset ('late' condition) of ipsilateral, contralateral, and bilateral (diotic) broadband noise, as well as in quiet. Thresholds were 2-4 dB better in the late than in the early condition for the three noise lateralities. The temporal effect held for carriers at equal sensation levels, confirming that it was not due to overshoot on carrier audibility. The temporal effect was larger for broadband than for low-band contralateral noises. Many aspects in the results were consistent with the noise activating the medial olivocochlear reflex (MOCR) and enhancing AM depth in the peripheral auditory response. Other aspects, however, indicate that central masking and adaptation unrelated to the MOCR also affect both carrier-tone and AM detection and are involved in the temporal effects.
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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.,Instituto de Investigación Biomédica de Salamanca, Universidad de Salamanca, Salamanca, Spain
| | - Almudena Eustaquio-Martín
- 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, Salamanca, Spain
| | - Luis E López-Bascuas
- Departamento de Psicología Básica I (Procesos Básicos), Universidad Complutense de Madrid, Madrid, 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, Salamanca, Spain. .,Departamento de Cirugía, Universidad de Salamanca, Salamanca, Spain.
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Abstract
OBJECTIVES In natural hearing, cochlear mechanical compression is dynamically adjusted via the efferent medial olivocochlear reflex (MOCR). These adjustments probably help understanding speech in noisy environments and are not available to the users of current cochlear implants (CIs). The aims of the present study are to: (1) present a binaural CI sound processing strategy inspired by the control of cochlear compression provided by the contralateral MOCR in natural hearing; and (2) assess the benefits of the new strategy for understanding speech presented in competition with steady noise with a speech-like spectrum in various spatial configurations of the speech and noise sources. DESIGN Pairs of CI sound processors (one per ear) were constructed to mimic or not mimic the effects of the contralateral MOCR on compression. For the nonmimicking condition (standard strategy or STD), the two processors in a pair functioned similarly to standard clinical processors (i.e., with fixed back-end compression and independently of each other). When configured to mimic the effects of the MOCR (MOC strategy), the two processors communicated with each other and the amount of back-end compression in a given frequency channel of each processor in the pair decreased/increased dynamically (so that output levels dropped/increased) with increases/decreases in the output energy from the corresponding frequency channel in the contralateral processor. Speech reception thresholds in speech-shaped noise were measured for 3 bilateral CI users and 2 single-sided deaf unilateral CI users. Thresholds were compared for the STD and MOC strategies in unilateral and bilateral listening conditions and for three spatial configurations of the speech and noise sources in simulated free-field conditions: speech and noise sources colocated in front of the listener, speech on the left ear with noise in front of the listener, and speech on the left ear with noise on the right ear. In both bilateral and unilateral listening, the electrical stimulus delivered to the test ear(s) was always calculated as if the listeners were wearing bilateral processors. RESULTS In both unilateral and bilateral listening conditions, mean speech reception thresholds were comparable with the two strategies for colocated speech and noise sources, but were at least 2 dB lower (better) with the MOC than with the STD strategy for spatially separated speech and noise sources. In unilateral listening conditions, mean thresholds improved with increasing the spatial separation between the speech and noise sources regardless of the strategy but the improvement was significantly greater with the MOC strategy. In bilateral listening conditions, thresholds improved significantly with increasing the speech-noise spatial separation only with the MOC strategy. CONCLUSIONS The MOC strategy (1) significantly improved the intelligibility of speech presented in competition with a spatially separated noise source, both in unilateral and bilateral listening conditions; (2) produced significant spatial release from masking in bilateral listening conditions, something that did not occur with fixed compression; and (3) enhanced spatial release from masking in unilateral listening conditions. The MOC strategy as implemented here, or a modified version of it, may be usefully applied in CIs and in hearing aids.
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24
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Fletcher MD, Krumbholz K, de Boer J. Effect of Contralateral Medial Olivocochlear Feedback on Perceptual Estimates of Cochlear Gain and Compression. J Assoc Res Otolaryngol 2016; 17:559-575. [PMID: 27550069 PMCID: PMC5112214 DOI: 10.1007/s10162-016-0574-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 06/17/2016] [Indexed: 11/16/2022] Open
Abstract
The active cochlear mechanism amplifies responses to low-intensity sounds, compresses the range of input sound intensities to a smaller output range, and increases cochlear frequency selectivity. The gain of the active mechanism can be modulated by the medial olivocochlear (MOC) efferent system, creating the possibility of top-down control at the earliest level of auditory processing. In humans, MOC function has mostly been measured by the suppression of otoacoustic emissions (OAEs), typically as a result of MOC activation by a contralateral elicitor sound. The exact relationship between OAE suppression and cochlear gain reduction, however, remains unclear. Here, we measured the effect of a contralateral MOC elicitor on perceptual estimates of cochlear gain and compression, obtained using the established temporal masking curve (TMC) method. The measurements were taken at a signal frequency of 2 kHz and compared with measurements of click-evoked OAE suppression. The elicitor was a broadband noise, set to a sound pressure level of 54 dB to avoid triggering the middle ear muscle reflex. Despite its low level, the elicitor had a significant effect on the TMCs, consistent with a reduction in cochlear gain. The amount of gain reduction was estimated as 4.4 dB on average, corresponding to around 18 % of the without-elicitor gain. As a result, the compression exponent increased from 0.18 to 0.27.
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Affiliation(s)
- Mark D Fletcher
- Medical Research Council Institute of Hearing Research, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK
- School of Psychology, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
- Institute of Sound and Vibration Research, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK
| | - Katrin Krumbholz
- Medical Research Council Institute of Hearing Research, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
| | - Jessica de Boer
- Medical Research Council Institute of Hearing Research, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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25
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Mishra SK, Dinger Z. Influence of medial olivocochlear efferents on the sharpness of cochlear tuning estimates in children. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:1060. [PMID: 27586737 DOI: 10.1121/1.4960550] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The present study objectively quantified the efferent-induced changes in the sharpness of cochlear tuning estimates and compared these alterations in cochlear tuning between adults and children. Click evoked otoacoustic emissions with and without contralateral broadband noise were recorded from 15 young adults and 14 children aged between 5 and 10 yrs. Time-frequency distributions of click evoked otoacoustic emissions were obtained via the S-transform, and the otoacoustic emission latencies were used to estimate the sharpness of cochlear tuning. Contralateral acoustic stimulation caused a significant reduction in the sharpness of cochlear tuning estimates in the low to mid frequency region, but had no effect in the higher frequencies (3175 and 4000 Hz). The magnitude of efferent-induced changes in cochlear tuning estimates was similar between adults and children. The current evidence suggests that the stimulation of the medial olivocochlear efferent neurons causes similar alterations in cochlear frequency selectivity in adults and children.
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Affiliation(s)
- Srikanta K Mishra
- Department of Special Education/Communication Disorders, New Mexico State University, Las Cruces, New Mexico 88003-8001, USA
| | - Zoë Dinger
- Department of Special Education/Communication Disorders, New Mexico State University, Las Cruces, New Mexico 88003-8001, USA
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Lopez-Poveda EA, Eustaquio-Martín A, Stohl JS, Wolford RD, Schatzer R, Wilson BS. Roles of the Contralateral Efferent Reflex in Hearing Demonstrated with Cochlear Implants. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 894:105-114. [DOI: 10.1007/978-3-319-25474-6_12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
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Lichtenhan JT, Wilson US, Hancock KE, Guinan JJ. Medial olivocochlear efferent reflex inhibition of human cochlear nerve responses. Hear Res 2016; 333:216-224. [PMID: 26364824 PMCID: PMC4788580 DOI: 10.1016/j.heares.2015.09.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/02/2015] [Indexed: 11/24/2022]
Abstract
Inhibition of cochlear amplifier gain by the medial olivocochlear (MOC) efferent system has several putative roles: aiding listening in noise, protection against damage from acoustic overexposure, and slowing age-induced hearing loss. The human MOC reflex has been studied almost exclusively by measuring changes in otoacoustic emissions. However, to help understand how the MOC system influences what we hear, it is important to have measurements of the MOC effect on the total output of the organ of Corti, i.e., on cochlear nerve responses that couple sounds to the brain. In this work we measured the inhibition produced by the MOC reflex on the amplitude of cochlear nerve compound action potentials (CAPs) in response to moderate level (52-60 dB peSPL) clicks from five, young, normal hearing, awake, alert, human adults. MOC activity was elicited by 65 dB SPL, contralateral broadband noise (CAS). Using tympanic membrane electrodes, approximately 10 h of data collection were needed from each subject to yield reliable measurements of the MOC reflex inhibition on CAP amplitudes from one click level. The CAS produced a 16% reduction of CAP amplitude, equivalent to a 1.98 dB effective attenuation (averaged over five subjects). Based on previous reports of efferent effects as functions of level and frequency, it is possible that much larger effective attenuations would be observed at lower sound levels or with clicks of higher frequency content. For a preliminary comparison, we also measured MOC reflex inhibition of DPOAEs evoked from the same ears with f2's near 4 kHz. The resulting effective attenuations on DPOAEs were, on average, less than half the effective attenuations on CAPs.
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Affiliation(s)
- J T Lichtenhan
- Washington University School of Medicine, Department of Otolaryngology, Saint Louis, MO 63110, USA.
| | - U S Wilson
- Washington University School of Medicine, Department of Otolaryngology, Saint Louis, MO 63110, USA; Missouri State University, Communications Sciences and Disorders, Springfield, MO 65897, USA
| | - K E Hancock
- Massachusetts Eye & Ear Infirmary, Eaton-Peabody Laboratory of Auditory Physiology, Boston, MA 02114, USA; Harvard Medical School, Department of Otology and Laryngology, Boston, MA 02115, USA
| | - J J Guinan
- Massachusetts Eye & Ear Infirmary, Eaton-Peabody Laboratory of Auditory Physiology, Boston, MA 02114, USA; Harvard Medical School, Department of Otology and Laryngology, Boston, MA 02115, USA
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Jürgens T, Clark NR, Lecluyse W, Meddis R. Exploration of a physiologically-inspired hearing-aid algorithm using a computer model mimicking impaired hearing. Int J Audiol 2016; 55:346-57. [DOI: 10.3109/14992027.2015.1135352] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Tim Jürgens
- Medizinische Physik, Forschungszentrum Neurosensorik and Cluster of Excellence ‘Hearing4all’, Carl-von-Ossietzky Universität Oldenburg, Oldenburg, Germany,
- Department of Psychology, University of Essex, Colchester, UK,
| | - Nicholas R. Clark
- Department of Psychology, University of Essex, Colchester, UK,
- Mimi Hearing Technologies GmbH, Berlin, Germany,
| | - Wendy Lecluyse
- Department of Psychology, University of Essex, Colchester, UK,
- Department of Children, Young People and Education, University Campus Suffolk, Ipswich, UK
| | - Ray Meddis
- Department of Psychology, University of Essex, Colchester, UK,
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Aguilar E, Johannesen PT, Lopez-Poveda EA. Contralateral efferent suppression of human hearing sensitivity. Front Syst Neurosci 2015; 8:251. [PMID: 25642172 PMCID: PMC4295548 DOI: 10.3389/fnsys.2014.00251] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 12/21/2014] [Indexed: 11/13/2022] Open
Abstract
The present study aimed at characterizing the suppressing effect of contralateral medial olivocochlear (MOC) efferents on human auditory sensitivity and mechanical cochlear responses at sound levels near behavioral thresholds. Absolute thresholds for pure tones of 500 and 4000 Hz with durations between 10-500 ms were measured in the presence and in the absence of a contralateral broadband noise. The intensity of the noise was fixed at 60 dB SPL to evoke the contralateral MOC reflex without evoking the middle-ear muscle reflex. In agreement with previously reported findings, thresholds measured without the contralateral noise decreased with increasing tone duration, and the rate of decrease was faster at 500 than at 4000 Hz. Contralateral stimulation increased thresholds by 1.07 and 1.72 dB at 500 and 4000 Hz, respectively. The mean increase (1.4 dB) just missed statistical significance (p = 0.08). Importantly, the across-frequency mean threshold increase was significantly greater for long than for short probes. This effect was more obvious at 4000 Hz than at 500 Hz. Assuming that thresholds depend on the MOC-dependent cochlear mechanical response followed by an MOC-independent, post-mechanical detection mechanism, the present results at 4000 Hz suggest that MOC efferent activation suppresses cochlear mechanical responses more at lower than at higher intensities across the range of intensities near threshold, while the results at 500 Hz suggest comparable mechanical suppression across the threshold intensity range. The results are discussed in the context of central masking and of auditory models of efferent suppression of cochlear mechanical responses.
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Affiliation(s)
- Enzo Aguilar
- Auditory Computation and Psychoacoustics, Instituto de Neurociencias de Castilla y León, Universidad de SalamancaSalamanca, Spain
- Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de SalamancaSalamanca, Spain
| | - Peter T. Johannesen
- Auditory Computation and Psychoacoustics, Instituto de Neurociencias de Castilla y León, Universidad de SalamancaSalamanca, Spain
- Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de SalamancaSalamanca, Spain
| | - Enrique A. Lopez-Poveda
- Auditory Computation and Psychoacoustics, Instituto de Neurociencias de Castilla y León, Universidad de SalamancaSalamanca, Spain
- Grupo de Audiología, Instituto de Investigación Biomédica de Salamanca, Universidad de SalamancaSalamanca, Spain
- Departamento de Cirugía, Facultad de Medicina, Universidad de SalamancaSalamanca, Spain
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Wojtczak M, Beim JA, Oxenham AJ. Exploring the role of feedback-based auditory reflexes in forward masking by schroeder-phase complexes. J Assoc Res Otolaryngol 2014; 16:81-99. [PMID: 25338224 DOI: 10.1007/s10162-014-0495-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 10/02/2014] [Indexed: 10/24/2022] Open
Abstract
Several studies have postulated that psychoacoustic measures of auditory perception are influenced by efferent-induced changes in cochlear responses, but these postulations have generally remained untested. This study measured the effect of stimulus phase curvature and temporal envelope modulation on the medial olivocochlear reflex (MOCR) and on the middle-ear muscle reflex (MEMR). The role of the MOCR was tested by measuring changes in the ear-canal pressure at 6 kHz in the presence and absence of a band-limited harmonic complex tone with various phase curvatures, centered either at (on-frequency) or well below (off-frequency) the 6-kHz probe frequency. The influence of possible MEMR effects was examined by measuring phase-gradient functions for the elicitor effects and by measuring changes in the ear-canal pressure with a continuous suppressor of the 6-kHz probe. Both on- and off-frequency complex tone elicitors produced significant changes in ear canal sound pressure. However, the pattern of results was not consistent with the earlier hypotheses postulating that efferent effects produce the psychoacoustic dependence of forward-masked thresholds on masker phase curvature. The results also reveal unexpectedly long time constants associated with some efferent effects, the source of which remains unknown.
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Affiliation(s)
- Magdalena Wojtczak
- Department of Psychology, University of Minnesota, N218 Elliott Hall, 75 East River Rd., Minneapolis, MN, 55455, USA,
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Jennings SG, Ahlstrom JB, Dubno JR. Computational modeling of individual differences in behavioral estimates of cochlear nonlinearities. J Assoc Res Otolaryngol 2014; 15:945-60. [PMID: 25266264 DOI: 10.1007/s10162-014-0486-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 09/01/2014] [Indexed: 02/07/2023] Open
Abstract
Temporal masking curves (TMCs) are often used to estimate cochlear compression in individuals with normal and impaired hearing. These estimates may yield a wide range of individual differences, even among subjects with similar quiet thresholds. This study used an auditory model to assess potential sources of variance in TMCs from 51 listeners in Poling et al. [J Assoc Res Otolaryngol, 13:91-108 (2012)]. These sources included threshold elevation, the contribution of outer and inner hair cell dysfunction to threshold elevation, compression of the off-frequency linear reference, and detection efficiency. Simulations suggest that detection efficiency is a primary factor contributing to individual differences in TMCs measured in normal-hearing subjects, while threshold elevation and the contribution of outer and inner hair cell dysfunction are primary factors in hearing-impaired subjects. Approximating the most compressive growth rate of the cochlear response from TMCs was achieved only in subjects with the highest detection efficiency. Simulations included off-frequency nonlinearity in basilar membrane and inner hair cell processing; however, this nonlinearity did not improve predictions, suggesting that other sources, such as the decay of masking and the strength of the medial olivocochlear reflex, may mimic off-frequency nonlinearity. Findings from this study suggest that sources of individual differences can play a strong role in behavioral estimates of compression, and these sources should be considered when using forward masking to study cochlear function in individual listeners or across groups of listeners.
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Affiliation(s)
- Skyler G Jennings
- Department of Communication Sciences and Disorders, The University of Utah, 390 South, 1530 East, BEHS 1201, Salt Lake City, UT, 84112, USA,
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Effects of contralateral acoustic stimulation on spontaneous otoacoustic emissions and hearing threshold fine structure. J Assoc Res Otolaryngol 2014; 15:897-914. [PMID: 25245498 DOI: 10.1007/s10162-014-0485-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 08/18/2014] [Indexed: 10/24/2022] Open
Abstract
Medial olivocochlear (MOC) influence on cochlear mechanics can be noninvasively, albeit indirectly, explored via the effects of contralateral acoustic stimulation (CAS) on otoacoustic emissions. CAS-mediated effects are particularly pronounced for spontaneous otoacoustic emissions (SOAEs), which are typically reduced in amplitude and shifted upward in frequency by CAS. We investigated whether similar frequency shifts and magnitude reductions were observed behaviorally in the fine structure of pure-tone hearing thresholds, a phenomenon thought to share a common underlying mechanism with SOAEs. In normal-hearing listeners, fine-resolution thresholds were obtained over a narrow frequency range centered on the frequency of an SOAE, both in the absence and presence of 60-dB SPL broadband CAS. While CAS shifted threshold fine structure patterns and SOAEs upward in frequency by a comparable amount, little reduction in the presence or depth of fine structure was observed at frequencies near those of SOAEs. In fact, CAS typically improved thresholds, particularly at threshold minima, and increased fine structure depth when reductions in the amplitude of the associated SOAE were less than 10 dB. Additional measurements made at frequencies distant from SOAEs, or near SOAEs that were more dramatically reduced in amplitude by the CAS, revealed that CAS tended to elevate thresholds and reduce threshold fine structure depth. The results suggest that threshold fine structure is sensitive to MOC-mediated changes in cochlear gain, but that SOAEs complicate the interpretation of threshold measurements at nearby frequencies, perhaps due to masking or other interference effects. Both threshold fine structure and SOAEs may be significant sources of intersubject and intrasubject variability in psychoacoustic investigations of MOC function.
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Wicher A, Moore BCJ. Effect of broadband and narrowband contralateral noise on psychophysical tuning curves and otoacoustic emissions. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2014; 135:2931-2941. [PMID: 24815273 DOI: 10.1121/1.4871358] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The relative effectiveness of narrowband and broadband noises in activating the efferent system was assessed by comparing the effect of contralateral stimulation (CS) with such sounds on psychophysical tuning curves (PTCs) determined in simultaneous masking, using signal frequencies of 1000 or 2000 Hz. To check that the CS stimuli used did activate the efferent system, distortion product otoacoustic emissions (DPOAEs) were also measured in the absence and presence of narrowband and broadband CS. The CS had no consistent effect on the masker level at the tips of the PTCs. A broadband pink noise CS consistently reduced the masker level required for threshold on both the low- and high-frequency sides of the PTCs for the 2000-Hz signal frequency. However, there were no consistent effects of the CS for any other case. The broadband pink noise CS had a greater effect in reducing DPOAE levels than the narrowband CS. The results provide psychophysical evidence supporting the idea that the efferent system is activated more effectively by a broadband than by a narrowband CS, at least for a signal frequency of 2000 Hz.
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Affiliation(s)
- Andrzej Wicher
- Institute of Acoustics, Faculty of Physics, Adam Mickiewicz University, 85 Umultowska, 61-614 Poznan, Poland
| | - Brian C J Moore
- Department of Experimental Psychology, Cambridge University, Downing Street, Cambridge CB2 3EB, England
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Bhagat SP, Kilgore C. Efferent-mediated reduction in cochlear gain does not alter tuning estimates from stimulus-frequency otoacoustic emission group delays. Neurosci Lett 2013; 559:132-5. [PMID: 24333175 DOI: 10.1016/j.neulet.2013.11.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/24/2013] [Accepted: 11/29/2013] [Indexed: 10/25/2022]
Abstract
The existence of efferent feedback from cortical and subcortical brain centers to the hair cells of the cochlea has been recognized for many years, but the role that efferent neurons play in hearing is not completely known. Stimulation of medial olivocochlear (MOC) efferent neurons suppresses sound-evoked basilar membrane responses and changes the tuning of single auditory nerve fibers in animal models. Both of these effects are linked to a MOC-induced reduction in the gain of the cochlear amplification provided by outer hair cells. To non-invasively examine the link between cochlear suppression and tuning in humans, stimulus-frequency otoacoustic emissions (SFOAEs) were recorded in conditions with and without contralateral acoustic stimulation (CAS) from 28 normal-hearing participants. SFOAEs were measured using clusters of closely-spaced probe-tone frequencies centered near 1.4 and 2.0kHz. An index of cochlear tuning, QERB, was calculated based on measures of SFOAE group delay at both 1.4 and 2.0kHz. A statistically significant (p<0.01) decrease in SFOAE levels acquired during CAS was detected only for the SFOAE cluster centered at 2kHz. No statistically significant differences in QERB were found between conditions with and without CAS at 1.4 and 2.0kHz. These findings suggest that in humans, tuning based on SFOAE group delay estimates is not appreciably altered at cochlear locations with MOC efferent-induced reductions in cochlear gain.
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Affiliation(s)
- Shaum P Bhagat
- Hearing Science Laboratory, School of Communication Sciences and Disorders, The University of Memphis, Memphis, TN 38105, United States.
| | - Chelsea Kilgore
- Hearing Science Laboratory, School of Communication Sciences and Disorders, The University of Memphis, Memphis, TN 38105, United States
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Lopez-Poveda EA, Aguilar E, Johannesen PT, Eustaquio-Martín A. Contralateral efferent regulation of human cochlear tuning: behavioural observations and computer model simulations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 787:47-54. [PMID: 23716208 DOI: 10.1007/978-1-4614-1590-9_6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In binaural listening, the two cochleae do not act as independent sound receptors; their functioning is linked via the contralateral medial olivo-cochlear reflex (MOCR), which can be activated by contralateral sounds. The present study aimed at characterizing the effect of a contralateral white noise (CWN) on psychophysical tuning curves (PTCs). PTCs were measured in forward masking for probe frequencies of 500 Hz and 4 kHz, with and without CWN. The sound pressure level of the probe was fixed across conditions. PTCs for different response criteria were measured by using various masker-probe time gaps. The CWN had no significant effects on PTCs at 4 kHz. At 500 Hz, by contrast, PTCs measured with CWN appeared broader, particularly for short gaps, and they showed a decrease in the masker level. This decrease was greater the longer the masker-probe time gap. A computer model of forward masking with efferent control of cochlear gain was used to explain the data. The model accounted for the data based on the assumption that the sole effect of the CWN was to reduce the cochlear gain by ∼6.5 dB at 500 Hz for low and moderate levels. It also suggested that the pattern of data at 500 Hz is the result of combined broad bandwidth of compression and off-frequency listening. Results are discussed in relation with other physiological and psychoacoustical studies on the effect of activation of MOCR on cochlear function.
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Affiliation(s)
- Enrique A Lopez-Poveda
- Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain.
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