Our long term goal is to understand the of the high variability in speech performance in implant listeners and to reduce the variability by improving performance, particularly in poorer performers (NIH Consensus Statement on Cochlear Implants, 1995). Our hypothesis is that the high variability across implant listeners is due to the differences in individual nerve survival and to differences in the coupling of the implanted electrodes to those surviving neurons. We hypothesize that speech recognition will be optimized if we can quantify the number and location of potential receiving channels in an individual implant patient and customize the delivery of speech information to those channels. Being able to deliver optimum speech cues to a given number of receiving channels depends on understanding of how to divide the speech cues into maximally information-bearing channels, a problem we term the analysis problem. Specifically, we will: (1) Quantify the number and location of potentiaI receiving channels in cochlear implant and brainstem implant patients. Seven measures (loudness summation, forward masking, simultaneous masking, gap detection, electrode discrimination, cortical dipole source localization, mismatch negativity) of electrode interaction will be collected to define the tonotopic specificity with which a spectral pattern can be represented in an individual patient. These measures will attempt to define the homogeneity and location of surviving neural elements, which will define the effective number and location of receiving channels in individual patients. Simultaneous and nonsimultaneous, psychophysical and electrophysiological, measures will be used at threshold and suprathreshold intensity levels. (2) Evaluate the spectral distribution of envelope cues in speech that are most critical for normal speech recognition (the analysis problem). Spectral and intensity cues will be independently and selectively degraded in an acoustic speech processor simulation of a cochlear implant. Phoneme and sentence recognition will be measured as a function of the number of channels to evaluate the importance function of each parameter. A secondary hypothesis is that we can trade off number of channels and corruption of some cues, e.g. that additional channels can offset the deleterious effect of an amplitude distortion or a spectral location shift. (3) Evaluate new speech processor designs to optimize the transmission of the most critical spectral-temporal cues of speech to individual implant patients based on electrode interaction measures. Psychophysical measures of electrode interaction (from #1 above) will be used to select the number and location of electrodes for use in a CIS-type speech processor. Given the number and location of the channels in an individual patient, speech envelope cues will be divided and presented to the selected electrodes in a manner that optimizes performance (determined in #2 above). Basic research in electrical stimulation of the human auditory system is important to advance our knowledge of basic auditory processing in normal and impaired listeners, and to improve the design and performance of implanted prostheses. This proposal will investigate two areas that we feel are fundamental to future improvements in cochlear implant performance: electrode interactions (which will define the number and location of potential receiving channels in an individual patient) and the tonotopic distribution of speech envelope cues (which will define the optimal way to analyze the speech information for delivery to a given number of channels).

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC001526-07
Application #
2683916
Study Section
Hearing Research Study Section (HAR)
Project Start
1992-05-01
Project End
2001-03-31
Budget Start
1998-04-01
Budget End
1999-03-31
Support Year
7
Fiscal Year
1998
Total Cost
Indirect Cost
Name
House Ear Institute
Department
Type
DUNS #
City
Los Angeles
State
CA
Country
United States
Zip Code
90057
Stelmach, Julia; Landsberger, David M; Padilla, Monica et al. (2017) Determining the minimum number of electrodes that need to be pitch matched to accurately estimate pitch matches across the array. Int J Audiol 56:894-899
Aronoff, Justin M; Stelmach, Julia; Padilla, Monica et al. (2016) Interleaved Processors Improve Cochlear Implant Patients' Spectral Resolution. Ear Hear 37:e85-90
Shannon, Robert V (2015) Auditory implant research at the House Ear Institute 1989-2013. Hear Res 322:57-66
Aronoff, Justin M; Padilla, Monica; Fu, Qian-Jie et al. (2015) Contralateral masking in bilateral cochlear implant patients: a model of medial olivocochlear function loss. PLoS One 10:e0121591
Goldsworthy, Raymond L; Shannon, Robert V (2014) Training improves cochlear implant rate discrimination on a psychophysical task. J Acoust Soc Am 135:334-41
Colletti, Liliana; Shannon, Robert V; Colletti, Vittorio (2014) The development of auditory perception in children after auditory brainstem implantation. Audiol Neurootol 19:386-94
Srinivasan, Arthi G; Padilla, Monica; Shannon, Robert V et al. (2013) Improving speech perception in noise with current focusing in cochlear implant users. Hear Res 299:29-36
Aronoff, Justin M; Landsberger, David M (2013) The development of a modified spectral ripple test. J Acoust Soc Am 134:EL217-22
Saoji, Aniket A; Landsberger, David M; Padilla, Monica et al. (2013) Masking patterns for monopolar and phantom electrode stimulation in cochlear implants. Hear Res 298:109-16
Shannon, Robert V (2012) Advances in auditory prostheses. Curr Opin Neurol 25:61-6

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