# Neural Pathophysiology and Suprathreshold Processing in Young Adults with Normal Thresholds

> **NIH NIH P50** · MASSACHUSETTS EYE AND EAR INFIRMARY · 2020 · $537,097

## Abstract

Project 3 Summary – Abstract
 Recent animal work from our laboratories suggests that the synapses between hair cells and
cochlear nerve terminals are the most vulnerable elements of the inner ear in both noise-induced and
age-related hearing loss. This synaptic degeneration does not affect hair cells or thresholds and,
therefore, hides behind a normal audiogram. However, this “hidden hearing loss” likely contributes to
decreased ability to understand speech, especially in noisy environments. It may also be an underlying
cause of tinnitus and hyperacusis. In animals, hidden hearing loss can be diagnosed by measuring the
suprathreshold amplitude of ABR wave I, the sound-evoked activity of the cochlear nerve.
 We have begun translating these insights from animal work to human studies. We have a pilot
study from audiometrically normal young adults showing significant correlations between
electrocochleographic measures consistent with cochlear synaptopathy and performance on difficult
speech recognition tasks.
 Here we propose to extend our pilot study into large-scale cross-sectional (Aim 1) and longitudinal
(Aim 2) studies of hidden hearing loss in college students with normal audiometric thresholds and
widely differing lifestyle with respect to aural abuse, as quantified by questionnaire. For Aim 1, we will
test the hypotheses that hidden hearing loss, defined as performance deficits on difficult word-
recognition tasks, is correlated with physiologic response deficits consistent with cochlear synaptopathy
and with estimated lifetime noise dose. Our outcome measures will be speech-in-noise tests. A
statistical model will test the correlation of these outcomes with noise-exposure history and with a
battery of physiological or psychophysical measures chosen to probe different stages of auditory
processing, i.e. distortion product otoacoustic emissions and high-frequency audiometry, SP/AP ratio
and envelope following responses to tones at high modulation frequencies, middle ear muscle or
medial olivocochlear reflexes, several variants of frequency following response probing monaural and
binaural temporal fine-structure processing, a temporal integration test of theories on stochastic
undersampling in cochlear synaptopathy, and tinnitus severity/handicap and loudness discomfort
level/hyperacusis. Using principal components analysis, cluster analysis and adaptive LASSO, we will
find the test combination that best predicts the outcome measures and assess the relative contributions
of peripheral vs. central pathophysiology to the observed performance deficits. In Aim 2, we will test the
hypothesis that hidden hearing loss progresses in young adults with regular and continued acoustic
overexposure by tracking a cohort of students over the five-year period of this project using the same
test battery as described in Aim 2.

## Key facts

- **NIH application ID:** 9987323
- **Project number:** 5P50DC015857-04
- **Recipient organization:** MASSACHUSETTS EYE AND EAR INFIRMARY
- **Principal Investigator:** Stéphane F. Maison
- **Activity code:** P50 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $537,097
- **Award type:** 5
- **Project period:** — → —

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9987323

## Citation

> US National Institutes of Health, RePORTER application 9987323, Neural Pathophysiology and Suprathreshold Processing in Young Adults with Normal Thresholds (5P50DC015857-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9987323. Licensed CC0.

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