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bioRxiv · 10.1101/2024.03.11.584489

Impact of Reduced Spectral Resolution on Temporal-Coherence-Based Source Segregation

Viswanathan, V.·Heinz, M. G.·Shinn-Cunningham, B. G.
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Abstract

1.Hearing-impaired listeners struggle to understand speech in noise, even when using cochlear implants (CIs) or hearing aids. Successful listening in noisy environments depends on the brains ability to organize a mixture of sound sources into distinct perceptual streams (i.e., source segregation). In normal-hearing listeners, temporal coherence of sound fluctuations across frequency channels supports this process by promoting grouping of elements belonging to a single acoustic source. We hypothesized that reduced spectral resolution--a hallmark of both electric/CI (from current spread) and acoustic (from broadened tuning) hearing with sensorineural hearing loss--degrades segregation based on temporal coherence. This is because reduced frequency resolution decreases the likelihood that a single sound source dominates the activity driving any specific channel; concomitantly, it increases the correlation in activity across channels. Consistent with our hypothesis, predictions from a physiologically plausible model of temporal-coherence-based segregation suggest that CI current spread reduces comodulation masking release (CMR; a correlate of temporal-coherence processing) and speech intelligibility in noise. These predictions are consistent with our behavioral data with simulated CI listening. Our model also predicts smaller CMR with increasing levels of outer-hair-cell damage. These results suggest that reduced spectral resolution relative to normal hearing impairs temporal-coherence-based segregation and speech-in-noise outcomes.

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Viswanathan, V., Heinz, M. G., Shinn-Cunningham, B. G.. 2024-03-13. Impact of Reduced Spectral Resolution on Temporal-Coherence-Based Source Segregation. https://doi.org/10.1101/2024.03.11.584489

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