Binaural hearing can provide greatly improved signal detection and speech understanding in back- ground noise. However, bilateral cochlear-implant (BICI) users demonstrate limited binaural unmasking (i.e., improved detection and understanding) of signals using speech processors. The gap in knowledge is that it is unclear why binaural unmasking nearly disappears when using speech processors. Until the binaural benefit gap is better understood and reduced, BICI users will have a relatively poor quality of life because of difficulty local- izing sounds and communicating in background noise. The long-term goal is to understand and maximize bin- aural benefits imparted by BICIs. The objective in this application is to understand the breakdown of binaural unmasking as the stimulus complexity increases and when signals are presented via speech processors. The central hypothesis is that BICI users' binaural unmasking is primarily stunted by the interaural decorrelation caused by stimulus-encoding-driven factors (modulations, current spread, and compression). Most studies have shown underwhelming binaural unmasking in BICI users, but few have considered the limiting role of interaural decorrelation. Our approach to investigate this problem is two-pronged: to better understand and increase un- masking in BICI listeners, and better understand and intentionally decrease unmasking in NH listeners (i.e., making them more like the BICI listeners). Then, we will compare perceptual performance to stimulus analyses of the physical waveforms, the stimuli processed by speech processing algorithms, and modeled neural repre- sentations of the electrical signals. With strong preliminary data in hand, the central hypothesis will be tested by pursuing four specific aims: (1) Measure the extent to which the internal representation of modulated single- electrode stimuli in BICI listeners is interaurally decorrelated; (2) Measure the extent to which current spread and compression limit binaural unmasking of tones in noise in multi-electrode stimulation; (3) Develop a model of across-frequency static and dynamic ILD processing; and (4) Measure the extent to which binaural unmasking of speech in noise is reduced by interaural decorrelation from modulations, current spread, and compression. The approach is innovative because it (1) investigates signal-based factors affecting binaural unmasking and other binaural benefits in BICIs and (2) investigates the role of ILDs to impart these benefits. The proposed research is significant because it helps us understand the barriers to larger binaural benefits in BICI users, which can inform changes to speech processing strategies and clinical device setting guidelines. Larger binaural un- masking and benefits will produce an important positive impact on CI users' quality of life because they will be better able to localize sounds and communicate in noisy environments.

Public Health Relevance

HEALTH RELEVANCE: The proposed research is relevant to public health because it investigates bionic implants as a technological intervention for people with severe-to-profound hearing loss. The proposed research seeks to improve bilateral (two-ear) implant functionality with a balance of basic and translational research and a future goal of creating clinically-usable bilateral implant device-setting tools. Thus, the proposed research is relevant to NIH's mission to develop new knowledge and improve technologies to help treat disability and in particular to NIDCD's mission to support efforts to create devices that substitute for lost and impaired sensory function.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
1R01DC014948-01A1
Application #
9177103
Study Section
Auditory System Study Section (AUD)
Program Officer
Donahue, Amy
Project Start
2016-06-01
Project End
2021-05-31
Budget Start
2016-06-01
Budget End
2017-05-31
Support Year
1
Fiscal Year
2016
Total Cost
$373,347
Indirect Cost
$123,347
Name
University of Maryland College Park
Department
Other Health Professions
Type
Schools of Arts and Sciences
DUNS #
790934285
City
College Park
State
MD
Country
United States
Zip Code
20742
Zaleski-King, Ashley; Goupell, Matthew J; Barac-Cikoja, Dragana et al. (2018) Bimodal Cochlear Implant Listeners' Ability to Perceive Minimal Audible Angle Differences. J Am Acad Audiol :
Goupell, Matthew J; Stakhovskaya, Olga A; Bernstein, Joshua G W (2018) Contralateral Interference Caused by Binaurally Presented Competing Speech in Adult Bilateral Cochlear-Implant Users. Ear Hear 39:110-123
Goupell, Matthew J; Stakhovskaya, Olga A (2018) Across-channel interaural-level-difference processing demonstrates frequency dependence. J Acoust Soc Am 143:645
Todd, Ann E; Goupell, Matthew J; Litovsky, Ruth Y (2017) The Relationship Between Intensity Coding and Binaural Sensitivity in Adults With Cochlear Implants. Ear Hear 38:e128-e141
Waked, Arifi; Dougherty, Sara; Goupell, Matthew J (2017) Vocoded speech perception with simulated shallow insertion depths in adults and children. J Acoust Soc Am 141:EL45
Stakhovskaya, Olga A; Goupell, Matthew J (2017) Lateralization of Interaural Level Differences with Multiple Electrode Stimulation in Bilateral Cochlear-Implant Listeners. Ear Hear 38:e22-e38
Litovsky, Ruth Y; Goupell, Matthew J; Kan, Alan et al. (2017) Use of Research Interfaces for Psychophysical Studies With Cochlear-Implant Users. Trends Hear 21:2331216517736464
Ehlers, Erica; Goupell, Matthew J; Zheng, Yi et al. (2017) Binaural sensitivity in children who use bilateral cochlear implants. J Acoust Soc Am 141:4264
Goupell, Matthew J; Kan, Alan; Litovsky, Ruth Y (2016) Spatial attention in bilateral cochlear-implant users. J Acoust Soc Am 140:1652
Brown, Andrew D; Rodriguez, Francisco A; Portnuff, Cory D F et al. (2016) Time-Varying Distortions of Binaural Information by Bilateral Hearing Aids: Effects of Nonlinear Frequency Compression. Trends Hear 20:

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