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.
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.
|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|
|Fogerty, Daniel; Ahlstrom, Jayne B; Bologna, William J et al. (2016) Glimpsing Speech in the Presence of Nonsimultaneous Amplitude Modulations From a Competing Talker: Effect of Modulation Rate, Age, and Hearing Loss. J Speech Lang Hear Res 59:1198-1207|
|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|
|Vaden Jr, Kenneth I; Kuchinsky, Stefanie E; Ahlstrom, Jayne B et al. (2016) Cingulo-Opercular Function During Word Recognition in Noise for Older Adults with Hearing Loss. Exp Aging Res 42:67-82|
|Jennings, Skyler G; Ahlstrom, Jayne B; Dubno, Judy R (2016) Effects of age and hearing loss on overshoot. J Acoust Soc Am 140:2481|
|Fogerty, Daniel; Ahlstrom, Jayne B; Bologna, William J et al. (2015) Sentence intelligibility during segmental interruption and masking by speech-modulated noise: Effects of age and hearing loss. J Acoust Soc Am 137:3487-501|
|Vaden Jr, Kenneth I; Kuchinsky, Stefanie E; Ahlstrom, Jayne B et al. (2015) Cortical activity predicts which older adults recognize speech in noise and when. J Neurosci 35:3929-37|
|Jennings, Skyler G; Ahlstrom, Jayne B; Dubno, Judy R (2014) Computational modeling of individual differences in behavioral estimates of cochlear nonlinearities. J Assoc Res Otolaryngol 15:945-60|
|Kuchinsky, Stefanie E; Ahlstrom, Jayne B; Cute, Stephanie L et al. (2014) Speech-perception training for older adults with hearing loss impacts word recognition and effort. Psychophysiology 51:1046-57|
|Chintanpalli, Ananthakrishna; Ahlstrom, Jayne B; Dubno, Judy R (2014) Computational model predictions of cues for concurrent vowel identification. J Assoc Res Otolaryngol 15:823-37|
Showing the most recent 10 out of 59 publications