# Physiological measures and perceptual consequences of noise-induced auditory synaptopathy in humans.

> **NIH NIH R01** · UNIVERSITY OF MINNESOTA · 2020 · $364,130

## Abstract

Recent studies in animals have shown that noise exposure causing temporary shifts in auditory thresholds can
lead to permanent and severe damage to the synaptic connections between the inner hair cells in the cochlea
and the auditory nerve. If such “auditory synaptopathy” occurs in humans, it would not be detected by current
standard audiometric tests, but could potentially explain why many people complain of excessive difficulty in
understanding speech in noisy backgrounds, despite having clinically normal hearing. The goal of this project
is to determine whether auditory synaptopathy occurs in humans and, if so, to develop clinically feasible tests
to diagnose it along with research tools to study its perceptual consequences. The project identifies three
populations who are considered to be potential suffers of auditory synaptopathy: 1) People who suffer from
tinnitus following noise exposure, but who have clinically normal hearing (i.e., normal audiometric thresholds
between 250 and 8000 Hz); 2) People who report having a history of exposure to loud sound, but have
clinically normal hearing; 3) People with mild-to-moderate hearing loss at high frequencies (> 2 kHz) but
clinically normal hearing at low frequencies. Results from these three groups will be compared with those from
an age- and gender-matched control group of people with normal hearing and no reported tinnitus or excessive
noise exposure. The project has a three-pronged approach, involving physiological, perceptual, and speech-
based measures. The first aim studies the potential effects of synaptopathy on two auditory reflexes: the
middle ear muscle reflex (MEMR) and the medial olivocochlear reflex (MOCR). Pilot data suggest that potential
sufferers of auditory synaptopathy have severely reduced MEMR, in line with previous animal studies. The
second aim investigates potential perceptual consequences of synaptopathy by measuring sensitivity to basic
acoustic attributes, such as amplitude and frequency modulation, with and without background noise. Pilot data
suggest that potential suffers of auditory synaptopathy are particularly susceptible to the effects of noise, even
if their performance in quiet is normal. The third aim studies speech perception in a variety of background
situations, including noise and speech interference with and without added reverberation. The experiments test
the prediction that performance will be affected by synaptopathy particularly in cases where the level of the
background noise is variable and unpredictable, and where the target and interfering speech are
distinguishable only by small differences in fundamental frequency or spatial location. The results from the
project will provide important new information and clinically relevant tests of a condition that potentially affects
millions of people in the US and worldwide. Reliable indicators and diagnoses of auditory synaptopathy in
humans will be crucial in the development of new pharmaceutical treatm...

## Key facts

- **NIH application ID:** 9893855
- **Project number:** 5R01DC015987-04
- **Recipient organization:** UNIVERSITY OF MINNESOTA
- **Principal Investigator:** MAGDALENA WOJTCZAK
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $364,130
- **Award type:** 5
- **Project period:** 2017-04-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9893855

## Citation

> US National Institutes of Health, RePORTER application 9893855, Physiological measures and perceptual consequences of noise-induced auditory synaptopathy in humans. (5R01DC015987-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9893855. Licensed CC0.

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