# Neural measures of temporal processing deficits affecting speech comprehension in listeners with normal hearing thresholds

> **NIH NIH F32** · CARNEGIE-MELLON UNIVERSITY · 2021 · $40,597

## Abstract

PROJECT SUMMARY/ABSTRACT
Some individuals with normal hearing thresholds (NHTs) demonstrate considerable challenges
perceiving speech in the presence of background noise. Evidence from recent studies suggests
that this impairment may be the result of cochlear synaptopathy (CS), degeneration of the
synapses between cochlear hair cells and the auditory nerve, observed in animal models following
exposure to high-intensity noise that does not permanently alter hearing thresholds. Still, it is not
known exactly how noise-induced CS would contribute to impairments in speech-in-noise
perception in humans with NHTs. CS engenders auditory nerve fiber degeneration and weakens
auditory nerve phase-locking to the precise timing information in auditory signals; therefore, the
goal of this research is to determine whether temporal processing impairments from noise-
induced CS are consistent with speech-in-noise perceptual deficits in listeners with NHTs. This
investigation will contrast listeners with high- and low-likelihood of noise-induced CS, as assessed
by a measure of summed auditory nerve fiber responses, on two mechanisms for segregating
speech streams that depend on accurate coding of precise timing information. Aim #1 of this
investigation will examine use of interaural timing difference cues for spatial attention to speech
streams and the degree to which attention to a target stream modulates cortical responses. Aim
#2 will utilize a novel task to assess participants’ ability to use pitch cues that can only be coded
by auditory nerve phase-locking to perceptually separate speech streams. Cortical entrainment
to the temporal envelope of speech, which has been shown to increase perceptual representation
of individual streams, will also be examined during this paradigm. Compared to participants with
a low likelihood of CS, it is expected that those with a high likelihood of having CS will perform
more poorly on tasks that require use of precise timing cues to segregate speech sounds from
competing streams. These listeners should also demonstrate lower cortical modulation and neural
synchrony to speech streams, demonstrating that bottom-up deficits in temporal encoding alter
neural representations of speech in the presence of competing sounds. These findings will
provide support for a link between noise-induced CS and impaired speech understanding in noise
in listeners with NHTs and will provide valuable knowledge of the contributors to this
communication impairment. This research will take place in an exceptional training environment
and the PI will be mentored by two knowledgeable, accomplished scientists. These experiments
will provide the PI with training in psychophysical task construction, brain activity recording, and
signal processing methods and will prepare her well for a career as an independent scientist.

## Key facts

- **NIH application ID:** 10020167
- **Project number:** 5F32DC018460-02
- **Recipient organization:** CARNEGIE-MELLON UNIVERSITY
- **Principal Investigator:** Mishaela T DiNino
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $40,597
- **Award type:** 5
- **Project period:** 2020-01-01 → 2021-10-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10020167

## Citation

> US National Institutes of Health, RePORTER application 10020167, Neural measures of temporal processing deficits affecting speech comprehension in listeners with normal hearing thresholds (5F32DC018460-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10020167. Licensed CC0.

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