# Auditory Mechanics and the Cochlear Amplifier 2020

> **NIH NIH R01** · COLUMBIA UNIVERSITY HEALTH SCIENCES · 2022 · $516,509

## Abstract

Project Summary / Abstract: Auditory Mechanics and Cochlear Amplification 2020
Sound input to the cochlea causes a frequency-sorted wave-pattern of sensory tissue motion that
conveys sound information to the auditory neurons, leading to hearing. A currently untreatable aspect
of hearing impairment is the deterioration of the cochlea's ability to sharply separate sound by
frequency. The cochlea's healthy frequency tuning is largely provided by the cochlear amplifier, an
outer-hair-cell-driven, place-frequency-localized electromechanical feedback mechanism that is both
powerful and fragile. This project's aims 1-3 explore the cell/structure basis of cochlear amplification.
The studies use intracochlear sensors and a cutting-edge imaging and vibrometry technology,
spectral-domain optical-coherence-tomography (SD-OCT). Localized measurements of mechanical
and electrical responses at and within the cochlea's sensory tissue will be made both in healthy
normal and in modified cochleae. Gerbils and guinea pigs are used and critical aspects of cochlear
amplification are compared in the two species in aim 2. In aim 1, measurements are made in
cochleae before and after intracochlear injection of substances that will modify tectorial membrane
(TM) mechanics. Because it governs transduction in hair cells, the TM plays a profound role in
cochlear amplification; our studies test hypotheses that are based on cochlear models and
measurements in isolated TMs and in TM-mutant mice. Aim 3 makes use of SD-OCT's penetrating
abilities to test previously untestable fluid-mechanical properties of the organ of Corti. Aim 4 explores
the transmission of sound to the cochlea by the middle ear, and how this transmission is modified by
feedback from the middle ear muscle, tensor tympani. In preliminary work, tensor tympani modified
transmission in a subtle, frequency-dependent manner that could be involved in focusing on particular
sound sources, for example during communication. Experiments in which tensor tympani is tensed
with voltage pulses will determine how the muscle affects the transmitted sound signal.

## Key facts

- **NIH application ID:** 10330593
- **Project number:** 5R01DC015362-07
- **Recipient organization:** COLUMBIA UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** ELIZABETH S. OLSON
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $516,509
- **Award type:** 5
- **Project period:** 2016-03-01 → 2026-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10330593

## Citation

> US National Institutes of Health, RePORTER application 10330593, Auditory Mechanics and the Cochlear Amplifier 2020 (5R01DC015362-07). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10330593. Licensed CC0.

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