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Cychosz M, Winn MB, Goupell MJ. How to vocode: Using channel vocoders for cochlear-implant research. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 155:2407-2437. [PMID: 38568143 PMCID: PMC10994674 DOI: 10.1121/10.0025274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 02/23/2024] [Indexed: 04/05/2024]
Abstract
The channel vocoder has become a useful tool to understand the impact of specific forms of auditory degradation-particularly the spectral and temporal degradation that reflect cochlear-implant processing. Vocoders have many parameters that allow researchers to answer questions about cochlear-implant processing in ways that overcome some logistical complications of controlling for factors in individual cochlear implant users. However, there is such a large variety in the implementation of vocoders that the term "vocoder" is not specific enough to describe the signal processing used in these experiments. Misunderstanding vocoder parameters can result in experimental confounds or unexpected stimulus distortions. This paper highlights the signal processing parameters that should be specified when describing vocoder construction. The paper also provides guidance on how to determine vocoder parameters within perception experiments, given the experimenter's goals and research questions, to avoid common signal processing mistakes. Throughout, we will assume that experimenters are interested in vocoders with the specific goal of better understanding cochlear implants.
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Affiliation(s)
- Margaret Cychosz
- Department of Linguistics, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - Matthew B Winn
- Department of Speech-Language-Hearing Sciences, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, College Park, Maryland 20742, USA
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Abramowitz JC, Goupell MJ, Milvae KD. Cochlear-Implant Simulated Signal Degradation Exacerbates Listening Effort in Older Listeners. Ear Hear 2024; 45:441-450. [PMID: 37953469 PMCID: PMC10922081 DOI: 10.1097/aud.0000000000001440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
OBJECTIVES Individuals with cochlear implants (CIs) often report that listening requires high levels of effort. Listening effort can increase with decreasing spectral resolution, which occurs when listening with a CI, and can also increase with age. What is not clear is whether these factors interact; older CI listeners potentially experience even higher listening effort with greater signal degradation than younger CI listeners. This study used pupillometry as a physiological index of listening effort to examine whether age, spectral resolution, and their interaction affect listening effort in a simulation of CI listening. DESIGN Fifteen younger normal-hearing listeners (ages 18 to 31 years) and 15 older normal-hearing listeners (ages 65 to 75 years) participated in this experiment; they had normal hearing thresholds from 0.25 to 4 kHz. Participants repeated sentences presented in quiet that were either unprocessed or vocoded, simulating CI listening. Stimuli frequency spectra were limited to below 4 kHz (to control for effects of age-related high-frequency hearing loss), and spectral resolution was decreased by decreasing the number of vocoder channels, with 32-, 16-, and 8-channel conditions. Behavioral speech recognition scores and pupil dilation were recorded during this task. In addition, cognitive measures of working memory and processing speed were obtained to examine if individual differences in these measures predicted changes in pupil dilation. RESULTS For trials where the sentence was recalled correctly, there was a significant interaction between age and spectral resolution, with significantly greater pupil dilation in the older normal-hearing listeners for the 8- and 32-channel vocoded conditions. Cognitive measures did not predict pupil dilation. CONCLUSIONS There was a significant interaction between age and spectral resolution, such that older listeners appear to exert relatively higher listening effort than younger listeners when the signal is highly degraded, with the largest effects observed in the eight-channel condition. The clinical implication is that older listeners may be at higher risk for increased listening effort with a CI.
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Affiliation(s)
- Jordan C. Abramowitz
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD 20742
| | - Matthew J. Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD 20742
| | - Kristina DeRoy Milvae
- Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY 14214
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Berg KA, Chen C, Noble JH, Dawant BM, Dwyer RT, Labadie RF, Gifford RH. Effects of the Number of Channels and Channel Stimulation Rate on Speech Recognition and Sound Quality Using Precurved Electrode Arrays. Am J Audiol 2023; 32:403-416. [PMID: 37249492 PMCID: PMC10468116 DOI: 10.1044/2023_aja-22-00032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 06/16/2022] [Accepted: 02/05/2023] [Indexed: 05/31/2023] Open
Abstract
PURPOSE This study investigated the relationship between the number of active electrodes, channel stimulation rate, and their interaction on speech recognition and sound quality measures while controlling for electrode placement. Cochlear implant (CI) recipients with precurved electrode arrays placed entirely within scala tympani and closer to the modiolus were hypothesized to be able to utilize more channels and possibly higher stimulation rates to achieve better speech recognition performance and sound quality ratings than recipients in previous studies. METHOD Participants included seven postlingually deafened adult CI recipients with Advanced Bionics Mid-Scala electrode arrays confirmed to be entirely within scala tympani using postoperative computerized tomography. Twelve conditions were tested using four, eight, 12, and 16 electrodes and channel stimulation rates of 600 pulse per second (pps), 1,200 pps, and each participant's maximum allowable rate (1,245-4,800 pps). Measures of speech recognition and sound quality were acutely assessed. RESULTS For the effect of channels, results showed no significant improvements beyond eight channels for all measures. For the effect of channel stimulation rate, results showed no significant improvements with higher rates, suggesting that 600 pps was sufficient for maximum speech recognition performance and sound quality ratings. However, across all conditions, there was a significant relationship between mean electrode-to-modiolus distance and all measures, suggesting that a lower mean electrode-to-modiolus distance was correlated with higher speech recognition scores and sound quality ratings. CONCLUSION These findings suggest that even well-placed precurved electrode array recipients may not be able to take advantage of more than eight channels or higher channel stimulation rates (> 600 pps), but that closer electrode array placement to the modiolus correlates with better outcomes for these recipients.
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Affiliation(s)
- Katelyn A. Berg
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN
| | - Chen Chen
- Research and Technology, Advanced Bionics, LLC, Valencia, CA
| | - Jack H. Noble
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN
| | - Benoit M. Dawant
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN
| | - Robert T. Dwyer
- Research and Technology, Advanced Bionics, LLC, Valencia, CA
| | - Robert F. Labadie
- Department of Otolaryngology-Head and Neck Surgery, Medical University of South Carolina, Charleston
| | - René H. Gifford
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN
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Warren SE, Atcherson SR. Evaluation of a clinical method for selective electrode deactivation in cochlear implant programming. Front Hum Neurosci 2023; 17:1157673. [PMID: 37063101 PMCID: PMC10101326 DOI: 10.3389/fnhum.2023.1157673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 03/09/2023] [Indexed: 03/31/2023] Open
Abstract
BackgroundCochlear implants are a neural prosthesis used to restore the perception of hearing in individuals with severe-to-profound hearing loss by stimulating the auditory nerve with electrical current through a surgically implanted electrode array. The integrity of the interface between the implanted electrode array and the auditory nerve contributes to the variability in outcomes experienced by cochlear implant users. Strategies to identify and eliminate poorly encoding electrodes have been found to be effective in improving outcomes with the device, but application is limited in a clinical setting.ObjectiveThe purpose of this study was to evaluate a clinical method used to identify and selectively deactivate cochlear implants (CI) electrodes related to poor electrode-neural interface.MethodsThirteen adult CI users participated in a pitch ranking task to identify indiscriminate electrode pairs. Electrodes associated with indiscriminate pairs were selectively deactivated, creating an individualized experimental program. Speech perception was evaluated in the baseline condition and with the experimental program before and after an acclimation period. Participant preference responses were recorded at each visit.ResultsStatistically significant improvements using the experimental program were found in at least one measure of speech perception at the individual level in four out of 13 participants when tested before acclimation. Following an acclimation period, ten out of 13 participants demonstrated statistically significant improvements in at least one measure of speech perception. Statistically significant improvements were found with the experimental program at the group level for both monosyllabic words (p = 0.006) and sentences in noise (p = 0.020). Additionally, ten participants preferred the experimental program prior to the acclimation period and eleven preferred the experimental program following the acclimation period.ConclusionResults from this study suggest that electrode deactivation may yield improvement in speech perception following an acclimation period. A majority of CI users in our study reported a preference for the experimental program. This method proved to be a suitable clinical strategy for identifying and deactivating poorly encoding electrodes in adult CI users.
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Affiliation(s)
- Sarah E. Warren
- Cochlear Implant Research Laboratory, School of Communication Sciences and Disorders, University of Memphis, Memphis, TN, United States
- Department of Audiology, Arkansas Children’s Hospital, Little Rock, AR, United States
- Department of Audiology and Speech Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
- *Correspondence: Sarah E. Warren,
| | - Samuel R. Atcherson
- Department of Audiology and Speech Pathology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
- Department of Otolaryngology–Head and Neck Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, United States
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Tinnemore AR, Montero L, Gordon-Salant S, Goupell MJ. The recognition of time-compressed speech as a function of age in listeners with cochlear implants or normal hearing. Front Aging Neurosci 2022; 14:887581. [PMID: 36247992 PMCID: PMC9557069 DOI: 10.3389/fnagi.2022.887581] [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: 03/01/2022] [Accepted: 08/29/2022] [Indexed: 11/13/2022] Open
Abstract
Speech recognition is diminished when a listener has an auditory temporal processing deficit. Such deficits occur in listeners over 65 years old with normal hearing (NH) and with age-related hearing loss, but their source is still unclear. These deficits may be especially apparent when speech occurs at a rapid rate and when a listener is mostly reliant on temporal information to recognize speech, such as when listening with a cochlear implant (CI) or to vocoded speech (a CI simulation). Assessment of the auditory temporal processing abilities of adults with CIs across a wide range of ages should better reveal central or cognitive sources of age-related deficits with rapid speech because CI stimulation bypasses much of the cochlear encoding that is affected by age-related peripheral hearing loss. This study used time-compressed speech at four different degrees of time compression (0, 20, 40, and 60%) to challenge the auditory temporal processing abilities of younger, middle-aged, and older listeners with CIs or with NH. Listeners with NH were presented vocoded speech at four degrees of spectral resolution (unprocessed, 16, 8, and 4 channels). Results showed an interaction between age and degree of time compression. The reduction in speech recognition associated with faster rates of speech was greater for older adults than younger adults. The performance of the middle-aged listeners was more similar to that of the older listeners than to that of the younger listeners, especially at higher degrees of time compression. A measure of cognitive processing speed did not predict the effects of time compression. These results suggest that central auditory changes related to the aging process are at least partially responsible for the auditory temporal processing deficits seen in older listeners, rather than solely peripheral age-related changes.
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Affiliation(s)
- Anna R. Tinnemore
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, College Park, MD, United States
- Department of Hearing and Speech Sciences, University of Maryland, College Park, College Park, MD, United States
- *Correspondence: Anna R. Tinnemore,
| | - Lauren Montero
- Department of Hearing and Speech Sciences, University of Maryland, College Park, College Park, MD, United States
| | - Sandra Gordon-Salant
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, College Park, MD, United States
- Department of Hearing and Speech Sciences, University of Maryland, College Park, College Park, MD, United States
| | - Matthew J. Goupell
- Neuroscience and Cognitive Science Program, University of Maryland, College Park, College Park, MD, United States
- Department of Hearing and Speech Sciences, University of Maryland, College Park, College Park, MD, United States
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Gifford RH, Sunderhaus LW, Holder JT, Berg KA, Dawant BM, Noble JH, Perkins E, Camarata S. Speech recognition as a function of the number of channels for pediatric cochlear implant recipients. JASA EXPRESS LETTERS 2022; 2:094403. [PMID: 36182337 PMCID: PMC9488908 DOI: 10.1121/10.0013428] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/26/2022] [Indexed: 06/16/2023]
Abstract
This study investigated the number of channels required for asymptotic speech recognition for ten pediatric cochlear implant (CI) recipients with precurved electrode arrays. Programs with 4-22 active electrodes were used to assess word and sentence recognition in noise. Children demonstrated significant performance gains up to 12 electrodes for continuous interleaved sampling (CIS) and up to 22 channels with 16 maxima. These data are consistent with the latest adult CI studies demonstrating that modern CI recipients have access to more than 8 independent channels and that both adults and children exhibit performance gains up to 22 channels.
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Affiliation(s)
- René H Gifford
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Linsey W Sunderhaus
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Jourdan T Holder
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Katelyn A Berg
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Benoit M Dawant
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Jack H Noble
- Department of Electrical and Computer Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - Elizabeth Perkins
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA , , , , , , ,
| | - Stephen Camarata
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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Berg KA, Noble JH, Dawant BM, Dwyer RT, Labadie RF, Gifford RH. Speech recognition as a function of the number of channels for Mid-Scala electrode array recipients. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 152:67. [PMID: 35931512 PMCID: PMC9984239 DOI: 10.1121/10.0012163] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
This study investigated the number of channels needed for maximum speech understanding and sound quality in 15 adult cochlear implant (CI) recipients with Advanced Bionics (AB) Mid-Scala electrode arrays completely within scala tympani. In experiment I, CI programs used a continuous interleaved sampling (CIS)-based strategy and 4-16 active electrodes. In experiment II, CI programs used an n-of-m strategy featuring 16 active electrodes with either 8- or 12-maxima. Speech understanding and sound quality measures were assessed. For CIS programs, participants demonstrated performance gains using up to 4-10 electrodes on speech measures and sound quality ratings. For n-of-m programs, there was no significant effect of maxima, suggesting 8-maxima is sufficient for this sample's maximum performance and sound quality. These results are largely consistent with previous studies using straight electrode arrays [e.g., Fishman, Shannon, and Slattery (1997). J. Speech Lang. Hear. Res. 40, 1201-1215; Friesen, Shannon, Baskent, and Wang (2001). J. Acoust. Soc. Am. 110, 1150-1163; Shannon, Cruz, and Galvin (2011). Audiol. Neurotol. 16, 113-123; Berg, Noble, Dawant, Dwyer, Labadie, and Gifford (2020). J. Acoust. Soc. Am. 147, 3646-3656] and in contrast with recent studies looking at cochlear precurved electrode arrays [e.g., Croghan, Duran, and Smith (2017). J. Acoust. Soc. Am. 142, EL537-EL543; Berg, Noble, Dawant, Dwuer, Labadie, and Gifford (2019b). J. Acoust. Soc. Am. 145, 1556-1564], which found continuous improvements up to 16 independent channels. These findings suggest that Mid-Scala electrode array recipients demonstrate similar channel independence to straight electrode arrays rather than other manufacturer's precurved electrode arrays.
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Affiliation(s)
- Katelyn A Berg
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, 1215 21st Avenue South, Nashville, Tennessee 37232, USA
| | - Jack H Noble
- Department of Electrical Engineering and Computer Science, Vanderbilt University, 2201 West End Avenue, Nashville, Tennessee 37235, USA
| | - Benoit M Dawant
- Department of Electrical Engineering and Computer Science, Vanderbilt University, 2201 West End Avenue, Nashville, Tennessee 37235, USA
| | - Robert T Dwyer
- Advanced Bionics, 28515 Westinghouse Place, Valencia, California 91355, USA
| | - Robert F Labadie
- Department of Otolaryngology, Vanderbilt University Medical Center, 1215 21st Avenue South, Nashville, Tennessee 37232, USA
| | - René H Gifford
- Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, 1215 21st Avenue South, Nashville, Tennessee 37232, USA
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Martin IA, Goupell MJ, Huang YT. Children's syntactic parsing and sentence comprehension with a degraded auditory signal. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:699. [PMID: 35232101 PMCID: PMC8816517 DOI: 10.1121/10.0009271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 10/15/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
During sentence comprehension, young children anticipate syntactic structures using early-arriving words and have difficulties revising incorrect predictions using late-arriving words. However, nearly all work to date has focused on syntactic parsing in idealized speech environments, and little is known about how children's strategies for predicting and revising meanings are affected by signal degradation. This study compares comprehension of active and passive sentences in natural and vocoded speech. In a word-interpretation task, 5-year-olds inferred the meanings of novel words in sentences that (1) encouraged agent-first predictions (e.g., The blicket is eating the seal implies The blicket is the agent), (2) required revising predictions (e.g., The blicket is eaten by the seal implies The blicket is the theme), or (3) weakened predictions by placing familiar nouns in sentence-initial position (e.g., The seal is eating/eaten by the blicket). When novel words promoted agent-first predictions, children misinterpreted passives as actives, and errors increased with vocoded compared to natural speech. However, when familiar words were sentence-initial that weakened agent-first predictions, children accurately interpreted passives, with no signal-degradation effects. This demonstrates that signal quality interacts with interpretive processes during sentence comprehension, and the impacts of speech degradation are greatest when late-arriving information conflicts with predictions.
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Affiliation(s)
- Isabel A Martin
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Yi Ting Huang
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
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