Cochlear implants (CI) are neural prostheses that provide meaningful auditory experience to more than 200,000 deaf patients worldwide. Despite significant success in quiet listening conditions, CIs currently provide only limited benefit in nosy real world situations. A critical limitation of the signal processing strategies employed by curren CIs is that they provide only a crude approximation of the processing that occurs in a healthy inner ear. In particular, current strategies only provide the envelope cues of band-pass filtered speech;the rapidly varying temporal fine structure cues associated with the carriers are simply not conveyed. Studies with normal-hearing listeners have shown that these temporal fine structure cues are converted into amplitude envelope cues by the peripheral auditory system.
The aim of the study in Phase I is to develop processing that mimics that fine-structure -to-envelope conversion for CIs. Processing strategies will be tested with CI users through use of an experimental interface that allows direct control of signals modulating the pulse streams to the CI electrodes. Experimental processing algorithms will be compared to users'personal processors on tests of speech reception in quiet and noise. If the results of Phase I show that the new signal processing strategies provide intelligibility benefits, work in Phase II will be aimd at: customizing the signal processing strategies for individual listeners;evaluating the benefits f the new signal processing strategies in reverberation;implementation of the new signal processing strategies on wearable processors;and field testing of cochlear implantees with prototype devices that incorporate the new signal processing strategies. Success in this project will result in enhanced speech reception by CI users in everyday noisy backgrounds.
Cochlear implantation is now the method of choice for dealing with the important public health issue of deafness. Cochlear implant users typically achieve success in understanding speech in quiet but their performance is severely compromised in backgrounds of interference. The proposed work will develop new signal processing strategies that will result in enhanced speech reception by CI users in everyday noisy backgrounds.
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|Swaminathan, Jayaganesh; Reed, Charlotte M; Desloge, Joseph G et al. (2014) Consonant identification using temporal fine structure and recovered envelope cues. J Acoust Soc Am 135:2078-90|