This research program aims to provide a better understanding of how basilar-membrane nonlinearities relate to speech recognition in noise and the extent to which a reduction or loss of nonlinearities for individuals with cochlear hearing los contributes to their communication difficulties. The unifying framework for the design of experiments and hypothesis testing is the active process in the cochlea, as revealed by measures of auditory function over a wide range of levels, using tonal and complex sounds, speech, and other sounds with fluctuating envelopes. In addition to high sensitivity and sharp tuning for low inputs, an important consequence of the active mechanism is the compressive nonlinearity in the basilar-membrane response. This process leads to level-dependent changes in masking, compression, tuning, and temporal effects, each of which has implications for speech recognition in noise. A thorough understanding of the negative consequences of reduced basilar-membrane nonlinearities is lacking due to the limited knowledge of nonlinear effects for complex sounds such as speech;small datasets from human subjects with large individual differences, especially for listeners with mild-to-moderate hearing loss;unknown effects of efferent activity;and uncertain interactions among level-dependent changes in masking, compression, and tuning. A comprehensive series of new experiments is planned within two broad aims, each with multiple components, to address key questions concerning the effects of basilar-membrane nonlinearities on auditory perception and recognition of speech.
Aim 1 measures nonlinearity effects on compression and tuning to test the hypothesis that nonlinearities in the basilar-membrane response underlie level-dependent changes in speech recognition in noise. Growth of masking, temporal masking, and distortion-product otoacoustic emissions (Aim 1.1), auditory-filter bandwidths (Aim 1.2), and growth of masking for speech (Aim 1.3) will be measured over a wide range of input levels for large numbers of subjects with normal hearing and mild-to-moderate hearing loss.
Aim 2 measures nonlinearity effects for sounds with fluctuating envelopes to test the hypothesis that level-dependent changes in the basilar-membrane response underlie changes in effective temporal envelopes with increases in level and play a role in detection and masking of fluctuating signals. Experiments in Aim 2 assess level-dependent changes in gap detection (Aim 2.1), modulation detection (Aim 2.2), and benefit from fluctuating maskers for speech recognition (Aim 2.3). To relate these results to basilar-membrane nonlinearities and disentangle interrelated nonlinear effects, level-dependent changes in compression and tuning will be measured and basilar-membrane responses inferred, as described in Aim 1, and supplemented by a well-established physiologically based computation model.

Public Health Relevance

Because speech is the principal signal used for human communication, it is essential to discover the bases and means for reducing the detrimental effects of cochlear hearing loss on the perception of speech, especially in challenging listening environments. A better understanding of these effects is essential if individuals with cochlear hearing loss are to achieve maximum benefit from amplified speech in adverse listening conditions.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
2R01DC000184-30A1
Application #
8302030
Study Section
Special Emphasis Panel (ZRG1-IFCN-M (03))
Program Officer
Donahue, Amy
Project Start
1981-12-01
Project End
2017-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
30
Fiscal Year
2012
Total Cost
$313,438
Indirect Cost
$100,938
Name
Medical University of South Carolina
Department
Otolaryngology
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
Bologna, William J; Vaden Jr, Kenneth I; Ahlstrom, Jayne B et al. (2018) Age effects on perceptual organization of speech: Contributions of glimpsing, phonemic restoration, and speech segregation. J Acoust Soc Am 144:267
McRackan, Theodore R; Fabie, Joshua E; Burton, Jane A et al. (2018) Earphone and Aided Word Recognition Differences in Cochlear Implant Candidates. Otol Neurotol 39:e543-e549
Dubno, Judy R (2018) Beyond the audiogram: application of models of auditory fitness for duty to assess communication in the real world. Int J Audiol 57:321-322
McRackan, Theodore R; Clinkscales, William B; Ahlstrom, Jayne B et al. (2018) Factors associated with benefit of active middle ear implants compared to conventional hearing aids. Laryngoscope 128:2133-2138
Settibhaktini, Harshavardhan; Chintanpalli, Ananthakrishna (2018) Modeling the level-dependent changes of concurrent vowel scores. J Acoust Soc Am 143:440
Eckert, Mark A; Matthews, Lois J; Dubno, Judy R (2017) Self-Assessed Hearing Handicap in Older Adults With Poorer-Than-Predicted Speech Recognition in Noise. J Speech Lang Hear Res 60:251-262
Fogerty, Daniel; Bologna, William J; Ahlstrom, Jayne B et al. (2017) Simultaneous and forward masking of vowels and stop consonants: Effects of age, hearing loss, and spectral shaping. J Acoust Soc Am 141:1133
Chintanpalli, Ananthakrishna; Ahlstrom, Jayne B; Dubno, Judy R (2016) Effects of age and hearing loss on concurrent vowel identification. J Acoust Soc Am 140:4142
Svec, Adam; Dubno, Judy R; Nelson, Peggy B (2016) Inherent envelope fluctuations in forward maskers: Effects of masker-probe delay for listeners with normal and impaired hearing. J Acoust Soc Am 139:1195-203
Kuchinsky, Stefanie E; Vaden Jr, Kenneth I; Ahlstrom, Jayne B et al. (2016) Task-Related Vigilance During Word Recognition in Noise for Older Adults with Hearing Loss. Exp Aging Res 42:50-66

Showing the most recent 10 out of 69 publications