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Easwar V, Purcell D, Wright T. Predicting Hearing aid Benefit Using Speech-Evoked Envelope Following Responses in Children With Hearing Loss. Trends Hear 2023; 27:23312165231151468. [PMID: 36946195 PMCID: PMC10034298 DOI: 10.1177/23312165231151468] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 12/24/2022] [Accepted: 12/30/2022] [Indexed: 03/23/2023] Open
Abstract
Electroencephalography could serve as an objective tool to evaluate hearing aid benefit in infants who are developmentally unable to participate in hearing tests. We investigated whether speech-evoked envelope following responses (EFRs), a type of electroencephalography-based measure, could predict improved audibility with the use of a hearing aid in children with mild-to-severe permanent, mainly sensorineural, hearing loss. In 18 children, EFRs were elicited by six male-spoken band-limited phonemic stimuli--the first formants of /u/ and /i/, the second and higher formants of /u/ and /i/, and the fricatives /s/ and /∫/--presented together as /su∫i/. EFRs were recorded between the vertex and nape, when /su∫i/ was presented at 55, 65, and 75 dB SPL using insert earphones in unaided conditions and individually fit hearing aids in aided conditions. EFR amplitude and detectability improved with the use of a hearing aid, and the degree of improvement in EFR amplitude was dependent on the extent of change in behavioral thresholds between unaided and aided conditions. EFR detectability was primarily influenced by audibility; higher sensation level stimuli had an increased probability of detection. Overall EFR sensitivity in predicting audibility was significantly higher in aided (82.1%) than unaided conditions (66.5%) and did not vary as a function of stimulus or frequency. EFR specificity in ascertaining inaudibility was 90.8%. Aided improvement in EFR detectability was a significant predictor of hearing aid-facilitated change in speech discrimination accuracy. Results suggest that speech-evoked EFRs could be a useful objective tool in predicting hearing aid benefit in children with hearing loss.
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Affiliation(s)
- Vijayalakshmi Easwar
- Department of Communication Sciences and Disorders & Waisman
Center, University of
Wisconsin–Madison, Madison, USA
- National
Acoustic Laboratories, Macquarie
University, Sydney, New South Wales, Australia
| | - David Purcell
- School of Communication Sciences and Disorders,
Western
University, London, Canada
- National Centre for Audiology, Western
University, London, Canada
| | - Trevor Wright
- Department of Communication Sciences and Disorders & Waisman
Center, University of
Wisconsin–Madison, Madison, USA
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Easwar V, Aiken S, Beh K, McGrath E, Galloy M, Scollie S, Purcell D. Variability in the Estimated Amplitude of Vowel-Evoked Envelope Following Responses Caused by Assumed Neurophysiologic Processing Delays. J Assoc Res Otolaryngol 2022; 23:759-769. [PMID: 36002663 PMCID: PMC9789223 DOI: 10.1007/s10162-022-00855-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 06/16/2022] [Indexed: 01/06/2023] Open
Abstract
Vowel-evoked envelope following responses (EFRs) reflect neural encoding of the fundamental frequency of voice (f0). Accurate analysis of EFRs elicited by natural vowels requires the use of methods like the Fourier analyzer (FA) to consider the production-related f0 changes. The FA's accuracy in estimating EFRs is, however, dependent on the assumed neurophysiological processing delay needed to time-align the f0 time course and the recorded electroencephalogram (EEG). For male-spoken vowels (f0 ~ 100 Hz), a constant 10-ms delay correction is often assumed. Since processing delays vary with stimulus and physiological factors, we quantified (i) the delay-related variability that would occur in EFR estimation, and (ii) the influence of stimulus frequency, non-f0 related neural activity, and the listener's age on such variability. EFRs were elicited by the low-frequency first formant, and mid-frequency second and higher formants of /u/, /a/, and /i/ in young adults and 6- to 17-year-old children. To time-align with the f0 time course, EEG was shifted by delays between 5 and 25 ms to encompass plausible response latencies. The delay-dependent range in EFR amplitude did not vary by stimulus frequency or age and was significantly smaller when interference from low-frequency activity was reduced. On average, the delay-dependent range was < 22% of the maximum variability in EFR amplitude that could be expected by noise. Results suggest that using a constant EEG delay correction in FA analysis does not substantially alter EFR amplitude estimation. In the present study, the lack of substantial variability was likely facilitated by using vowels with small f0 ranges.
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Affiliation(s)
- Vijayalakshmi Easwar
- Department of Communication Sciences and Disorders & Waisman Center, University of Wisconsin-Madison, Madison, WI, USA.
- National Acoustic Laboratories, Sydney, Australia.
| | - Steven Aiken
- School of Communication Sciences and Disorders, Dalhousie University, Nova Scotia, Canada
| | - Krystal Beh
- Department of Communication Sciences and Disorders & National Centre for Audiology, Western University, London, ON, Canada
| | - Emma McGrath
- Department of Communication Sciences and Disorders & Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Mary Galloy
- Department of Communication Sciences and Disorders & Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Susan Scollie
- Department of Communication Sciences and Disorders & National Centre for Audiology, Western University, London, ON, Canada
| | - David Purcell
- Department of Communication Sciences and Disorders & National Centre for Audiology, Western University, London, ON, Canada
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Performance of Statistical Indicators in the Objective Detection of Speech-Evoked Envelope Following Responses. Ear Hear 2022; 43:1669-1677. [PMID: 35499293 DOI: 10.1097/aud.0000000000001232] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES To assess the sensitivity of statistical indicators used for the objective detection of speech-evoked envelope following responses (EFRs) in infants and adults. DESIGN Twenty-three adults and 21 infants with normal hearing participated in this study. A modified/susa∫i/speech token was presented at 65 dB SPL monoaurally. Presentation level in infants was corrected using in-ear measurements. EFRs were recorded between high forehead and ipsilateral mastoid. Statistical post-processing was completed using F -test, Magnitude-Square Coherence, Rayleigh test, Rayleigh-Moore test, and Hotelling's T 2 test. Logistic regression models assessed the sensitivity of each statistical indicator in both infants and adults as a function of testing duration. RESULTS The Rayleigh-Moore and Rayleigh tests were the most sensitive statistical indicators for speech-evoked EFR detection in infants. Comparatively, Magnitude-Square Coherence and Hotelling's T 2 also provide clinical benefit for infants in all conditions after ~30 minutes of testing, whereas the F -test failed to detect responses to EFRs elicited by vowels with accuracy greater than chance. In contrast, the F-test was the most sensitive for vowel-elicited response detection for adults in short tests (<10 minute) and performed comparatively with the Rayleigh-Moore and Rayleigh test during longer test durations. Decreased sensitivity was observed in infants relative to adults across all testing durations and statistical indicators, but the effects were largest in low frequency stimuli and seemed to be mostly, but not wholly, caused by differences in response amplitude. CONCLUSIONS The choice of statistical indicator significantly impacts the sensitivity of speech-evoked EFR detection. In both groups and for all stimuli, the Rayleigh test and Rayleigh-Moore tests have high sensitivity. Differences in EFR detection are present between infants and adults regardless of statistical indicator; however, these effects are largest for low-frequency EFR stimuli and for amplitude-based statistical indicators.
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Easwar V, Purcell D, Lasarev M, McGrath E, Galloy M. Speech-Evoked Envelope Following Responses in Children and Adults. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2022; 65:4009-4023. [PMID: 36129844 DOI: 10.1044/2022_jslhr-22-00156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
PURPOSE Envelope following responses (EFRs) could be useful for objectively evaluating audibility of speech in children who are unable to participate in routine clinical tests. However, relative to adults, the characteristics of EFRs elicited by frequency-specific speech and their utility in predicting audibility in children are unknown. METHOD EFRs were elicited by the first (F1) and second and higher formants (F2+) of male-spoken vowels /u/ and /i/ and by fricatives /ʃ/ and /s/ in the token /suʃi/ presented at 15, 35, 55, 65, and 75 dB SPL. The F1, F2+, and fricatives were low-, mid-, and high-frequency dominant, respectively. EFRs were recorded between the vertex and the nape from twenty-three 6- to 17-year-old children and 21 young adults with normal hearing. Sensation levels of stimuli were estimated based on behavioral thresholds. RESULTS In children, amplitude decreased with age for /ʃ/-elicited EFRs but remained stable for low- and mid-frequency stimuli. As a group, EFR amplitude and phase coherence did not differ from that of adults. EFR sensitivity (proportion of audible stimuli detected) and specificity (proportion of inaudible stimuli not detected) did not vary between children and adults. Consistent with previous work, EFR sensitivity increased with stimulus frequency and level. The type of statistical indicator used for EFR detection did not influence accuracy in children. CONCLUSIONS Adultlike EFRs in 6- to 17-year-old typically developing children suggest mature envelope encoding for low- and mid-frequency stimuli. EFR sensitivity and specificity in children, when considering a wide range of stimulus levels and audibility, are ~77% and ~92%, respectively. SUPPLEMENTAL MATERIAL https://doi.org/10.23641/asha.21136171.
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Affiliation(s)
- Vijayalakshmi Easwar
- Department of Communication Sciences and Disorders and Waisman Center, University of Wisconsin-Madison
- National Acoustic Laboratories, Sydney, New South Wales, Australia
| | - David Purcell
- School of Communication Sciences and Disorders, Western University, London, Ontario, Canada
| | - Michael Lasarev
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison
| | - Emma McGrath
- Department of Communication Sciences and Disorders and Waisman Center, University of Wisconsin-Madison
| | - Mary Galloy
- Department of Communication Sciences and Disorders and Waisman Center, University of Wisconsin-Madison
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Easwar V, Chung L. The influence of phoneme contexts on adaptation in vowel-evoked envelope following responses. Eur J Neurosci 2022; 56:4572-4582. [PMID: 35804282 PMCID: PMC9543495 DOI: 10.1111/ejn.15768] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 02/25/2022] [Accepted: 07/06/2022] [Indexed: 11/28/2022]
Abstract
Repeated stimulus presentation leads to neural adaptation and consequent amplitude reduction in vowel-evoked envelope following responses (EFRs)-a response that reflects neural activity phase-locked to envelope periodicity. EFRs are elicited by vowels presented in isolation or in the context of other phonemes such as in syllables. While context phonemes could exert some forward influence on vowel-evoked EFRs, they may reduce the degree of adaptation. Here, we evaluated whether the properties of context phonemes between consecutive vowel stimuli influence adaptation. EFRs were elicited by the low-frequency first formant (resolved harmonics) and mid-to-high frequency second and higher formants (unresolved harmonics) of a male-spoken/i/when the presence, number, and predictability of context phonemes (/s/, /a/, /∫/, /u/) between vowel repetitions varied. Monitored over four iterations of /i/, adaptation was evident only for EFRs elicited by the unresolved harmonics. EFRs elicited by the unresolved harmonics decreased in amplitude by ~16-20 nV (10-17%) after the first presentation of/i/and remained stable thereafter. EFR adaptation was reduced by the presence of a context phoneme, but the reduction did not change with their number or predictability. The presence of a context phoneme, however, attenuated EFRs by a degree similar to that caused by adaptation (~21-23 nV). Such a trade-off in the short- and long-term influence of context phonemes suggests that the benefit of interleaving EFR-eliciting vowels with other context phonemes depends on whether the use of consonant-vowel syllables is critical to improve the validity of EFR applications.
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Affiliation(s)
- Vijayalakshmi Easwar
- Department of Communication Sciences & Disorders, University of Wisconsin-Madison, Madison, USA.,Waisman Center, University of Wisconsin-Madison, Madison, USA
| | - Lauren Chung
- Department of Communication Sciences & Disorders, University of Wisconsin-Madison, Madison, USA.,Waisman Center, University of Wisconsin-Madison, Madison, USA
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Sensitivity of Vowel-Evoked Envelope Following Responses to Spectra and Level of Preceding Phoneme Context. Ear Hear 2022; 43:1327-1335. [DOI: 10.1097/aud.0000000000001190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cheng FY, Smith S. Objective Detection of the Speech Frequency Following Response (sFFR): A Comparison of Two Methods. Audiol Res 2022; 12:89-94. [PMID: 35200259 PMCID: PMC8869319 DOI: 10.3390/audiolres12010010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 02/01/2023] Open
Abstract
Speech frequency following responses (sFFRs) are increasingly used in translational auditory research. Statistically-based automated sFFR detection could aid response identification and provide a basis for stopping rules when recording responses in clinical and/or research applications. In this brief report, sFFRs were measured from 18 normal hearing adult listeners in quiet and speech-shaped noise. Two statistically-based automated response detection methods, the F-test and Hotelling’s T2 (HT2) test, were compared based on detection accuracy and test time. Similar detection accuracy across statistical tests and conditions was observed, although the HT2 test time was less variable. These findings suggest that automated sFFR detection is robust for responses recorded in quiet and speech-shaped noise using either the F-test or HT2 test. Future studies evaluating test performance with different stimuli and maskers are warranted to determine if the interchangeability of test performance extends to these conditions.
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Abstract
OBJECTIVES To evaluate sensation level (SL)-dependent characteristics of envelope following responses (EFRs) elicited by band-limited speech dominant in low, mid, and high frequencies. DESIGN In 21 young normal hearing adults, EFRs were elicited by 8 male-spoken speech stimuli-the first formant, and second and higher formants of /u/, /a/ and /i/, and modulated fricatives, /∫/ and /s/. Stimulus SL was computed from behaviorally measured thresholds. RESULTS At 30 dB SL, the amplitude and phase coherence of fricative-elicited EFRs were ~1.5 to 2 times higher than all vowel-elicited EFRs, whereas fewer and smaller differences were found among vowel-elicited EFRs. For all stimuli, EFR amplitude and phase coherence increased by roughly 50% for every 10 dB increase in SL between ~0 and 50 dB. CONCLUSIONS Stimulus and frequency dependency in EFRs exist despite accounting for differences in audibility of speech sounds. The growth rate of EFR characteristics with SL is independent of stimulus and its frequency.
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Easwar V, Boothalingam S, Flaherty R. Fundamental frequency-dependent changes in vowel-evoked envelope following responses. Hear Res 2021; 408:108297. [PMID: 34229221 DOI: 10.1016/j.heares.2021.108297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 06/03/2021] [Accepted: 06/09/2021] [Indexed: 10/21/2022]
Abstract
Scalp-recorded envelope following responses (EFRs) provide a non-invasive method to assess the encoding of the fundamental frequency (f0) of voice that is important for speech understanding. It is well-known that EFRs are influenced by voice f0. However, this effect of f0 has not been examined independent of concomitant changes in spectra or neural generators. We evaluated the effect of voice f0 on EFRs while controlling for vowel formant characteristics and potentially avoiding significant changes in dominant neural generators using a small f0 range. EFRs were elicited by a male-spoken vowel /u/ (average f0 = 100.4 Hz) and its lowered f0 version (average f0 = 91.9 Hz) with closely matched formant characteristics. Vowels were presented to each ear of 17 young adults with normal hearing. EFRs were simultaneously recorded between the vertex and the nape, and the vertex and the ipsilateral mastoid-the two most common electrode montages used for EFRs. Our results indicate that when vowel formant characteristics are matched, an increase in f0 by 8.5 Hz reduces EFR amplitude by 25 nV, phase coherence by 0.05 and signal-to-noise ratio by 3.5 dB, on average. The reduction in EFR characteristics was similar across ears of stimulation and the two montages used. These findings will help parse the influence of f0 or stimulus spectra on EFRs when both co-vary.
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Affiliation(s)
- Vijayalakshmi Easwar
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, United States; Waisman Center, University of Wisconsin-Madison, United States
| | - Sriram Boothalingam
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, United States; Waisman Center, University of Wisconsin-Madison, United States
| | - Regan Flaherty
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, United States; Waisman Center, University of Wisconsin-Madison, United States
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Montage-related Variability in the Characteristics of Envelope Following Responses. Ear Hear 2021; 42:1436-1440. [PMID: 33900208 DOI: 10.1097/aud.0000000000001018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The study aimed to compare two electrode montages commonly used for recording speech-evoked envelope following responses. DESIGN Twenty-three normal-hearing adults participated in this study. EFRs were elicited by a naturally spoken, modified /susa∫i/ stimulus presented at 65 dB SPL monaurally. EFRs were recorded using two single-channel electrode montages: Cz-nape and Fz-ipsilateral mastoid, where the noninverting and inverting sites were the vertex and nape, and the high forehead and ipsilateral mastoid, respectively. Montage order was counterbalanced across participants. RESULTS Envelope following responses amplitude and phase coherence were significantly higher overall in the Cz-nape montage with no significant differences in noise amplitude. Post hoc testing on montage effects in response amplitude and phase coherence was not significant for individual stimuli. The Cz-nape montage also resulted in a greater number of detections and analyzed using the Hotelling's T2. CONCLUSIONS Electrode montage influences the estimated characteristics of speech-evoked EFRs.
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Easwar V, Scollie S, Lasarev M, Urichuk M, Aiken SJ, Purcell DW. Characteristics of Speech-Evoked Envelope Following Responses in Infancy. Trends Hear 2021; 25:23312165211004331. [PMID: 34251887 PMCID: PMC8278440 DOI: 10.1177/23312165211004331] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/04/2021] [Accepted: 03/01/2021] [Indexed: 11/21/2022] Open
Abstract
Envelope following responses (EFRs) may be a useful tool for evaluating the audibility of speech sounds in infants. The present study aimed to evaluate the characteristics of speech-evoked EFRs in infants with normal hearing, relative to adults, and identify age-dependent changes in EFR characteristics during infancy. In 42 infants and 21 young adults, EFRs were elicited by the first (F1) and the second and higher formants (F2+) of the vowels /u/, /a/, and /i/, dominant in low and mid frequencies, respectively, and by amplitude-modulated fricatives /s/ and /∫/, dominant in high frequencies. In a subset of 20 infants, the in-ear stimulus level was adjusted to match that of an average adult ear (65 dB sound pressure level [SPL]). We found that (a) adult-infant differences in EFR amplitude, signal-to-noise ratio, and intertrial phase coherence were larger and spread across the frequency range when in-ear stimulus level was adjusted in infants, (b) adult-infant differences in EFR characteristics were the largest for low-frequency stimuli, (c) infants demonstrated adult-like phase coherence when they received a higher (i.e., unadjusted) stimulus level, and (d) EFR phase coherence and signal-to-noise ratio changed with age in the first year of life for a few F2+ vowel stimuli in a level-specific manner. Together, our findings reveal that development-related changes in EFRs during infancy likely vary by stimulus frequency, with low-frequency stimuli demonstrating the largest adult-infant differences. Consistent with previous research, our findings emphasize the significant role of stimulus level calibration methods while investigating developmental trends in EFRs.
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Affiliation(s)
- Vijayalakshmi Easwar
- Department of Communication Sciences and Disorders, University of Wisconsin-Madison, Madison, United States
- Waisman Center, University of Wisconsin-Madison, Madison, United States
- National Centre for Audiology, Western University, London, Ontario, Canada
| | - Susan Scollie
- National Centre for Audiology, Western University, London, Ontario, Canada
- School of Communication Sciences and Disorders, Western University, London, Ontario, Canada
| | - Michael Lasarev
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, United States
| | - Matthew Urichuk
- School of Communication Sciences and Disorders, Western University, London, Ontario, Canada
- Health and Rehabilitation Sciences, Western University, London, Ontario, Canada
| | - Steven J Aiken
- School of Communication Sciences and Disorders, Dalhousie University, Halifax, Nova Scotia, Canada
| | - David W Purcell
- National Centre for Audiology, Western University, London, Ontario, Canada
- School of Communication Sciences and Disorders, Western University, London, Ontario, Canada
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