# Hidden Hearing Loss: A View from the Brain

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2021 · $505,841

## Abstract

Abstract
The concept of “hidden” hearing loss challenges the idea that temporary threshold shifts (TTS) reflect a return
to normal hearing. Recent studies indicate that after noise-exposure that produces TTS, and thus clinically
'normal' audiograms, there is nonetheless permanent damage to auditory nerve fiber (ANF) synapses with
cochlear inner hair cells. Hidden hearing loss is a potential major health issue, as human temporal bone and
ABR studies suggest it is common in humans. The remaining perceptual deficits in humans with clinically
normal audiograms reflect temporal coding problems likely due to loss of the high threshold, low spontaneous
rate ANFs, which are preferentially affected after TTS. The primary central targets of high-threshold ANFs
reside in the small cell cap (SCC) of the cochlear nucleus (CN). High-threshold ANFs and their SCC targets
display large dynamic ranges and superior suprathreshold tuning and temporal coding, which are essential for
speech perception in noisy environments. The SCC occupies a large proportion of the CN in humans and is
therefore poised to play a major role in central mechanisms of hidden hearing loss. The SCC is unique also as
a putative recipient and projection area of medial olivocochlear (MOC) neurons. The overall hypothesis of this
proposal is that the SCC plays a major role in suprathreshold sound coding and that this coding is highly
susceptible to degradation by hidden hearing loss. The goal of this series of studies is to elucidate the cochlea-
SCC-MOC circuit in normal and noise-damaged animals with hidden hearing loss, using state-of-the-art
optogenetics, multichannel single unit physiology, tract tracing and sophisticated immunohistochemical
methods.

## Key facts

- **NIH application ID:** 10174907
- **Project number:** 5R01DC017119-04
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** SUSAN E SHORE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $505,841
- **Award type:** 5
- **Project period:** 2018-06-07 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10174907

## Citation

> US National Institutes of Health, RePORTER application 10174907, Hidden Hearing Loss: A View from the Brain (5R01DC017119-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10174907. Licensed CC0.

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