# Auditory neural coding of speech

> **NIH NIH R01** · MASSACHUSETTS EYE AND EAR INFIRMARY · 2022 · $565,055

## Abstract

Project Summary/Abstract
Everyday listening environments often comprise noise and acoustic reflections off surrounding surfaces, together known
as reverberation. While normal-hearing listeners can converse in such environments with little effort, those with hearing
loss find them challenging. Despite the ubiquity of reverberation, little is known about the neural mechanisms for robust
listening in reverberation and even less is known about the combined effects of noise and reverberation on neural
coding. The proposed studies will, for the first time, investigate how speech-like stimuli presented in realistic
reverberation are encoded in the auditory midbrain of an unanesthetized rabbit model. The auditory midbrain is known
to play a key role in the precedence effect, which helps accurate sound localization in reverberation. Three specific aims
will use stimuli of increasing realism to address fundamental questions. Because modulations of the amplitude envelope
are essential for speech reception, Specific Aim 1 will focus on amplitude modulated (AM) stimuli. We will test the
hypothesis that a previously identified “reverberant advantage” in the temporal coding of AM sounds occurs because
the neurons sensitivity to AM is enhanced by their sensitivity to the fluctuations in interaural coherence that necessarily
accompany AM in reverberation. If verified, this hypothesis would highlight the importance of preserving dynamic
binaural cues in hearing aids. Specific Aim 2 will directly test how natural speech is coded by midbrain auditory neurons
in various amounts of reverberation. We will use modern techniques for stimulus reconstruction from neural population
activity to quantitatively assess the robustness of neural coding in reverberation and test whether adaptation to the
statistics of the reverberant environment contributes to robust coding. Specific Aim 3 will extend the Aim 2 results to
the common case when reverberation is combined with background noise. Using an innovative technique to
independently control the amount of reverberation in a speech target and a noise interferer, we will disentangle how
the neural coding of the target is affected by each. We will determine how the degradation in the interferer binaural
cues caused by reverberation reduces the benefit of spatial separation between target and interferer for neural coding
of the target. Together, these studies will increase fundamental understanding of the neural mechanisms for robust
neural coding in reverberation. The findings will guide the development of new processing strategies for hearing aids
and cochlear implants that would improve speech reception in everyday challenging environments.

## Key facts

- **NIH application ID:** 10430200
- **Project number:** 5R01DC002258-28
- **Recipient organization:** MASSACHUSETTS EYE AND EAR INFIRMARY
- **Principal Investigator:** Bertrand Delgutte
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $565,055
- **Award type:** 5
- **Project period:** 1995-01-01 → 2024-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10430200

## Citation

> US National Institutes of Health, RePORTER application 10430200, Auditory neural coding of speech (5R01DC002258-28). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10430200. Licensed CC0.

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