# Constraints on binaural sensitivity via bilateral bone conduction

> **NIH NIH R21** · UNIVERSITY OF WASHINGTON · 2021 · $155,500

## Abstract

Project Description
 In normal hearing, sound reaches the cochlea via the tympanic membrane and middle ear, i.e. air
conduction (AC). A secondary mode of hearing, known as bone conduction (BC), bypasses the conductive
pathway to cause pressure fluctuations within the cochlea primarily via vibration of surrounding bone. While the
contributions of BC to audition under normal listening conditions are minimal, BC signals are readily passed to
the cochlea using mechanical transducers, and hearing tests employing such transducers have been used for
over a century to diagnose conductive hearing pathologies. For individuals with conductive hearing loss, BC
stimulation via modern BC hearing aids can improve audibility in the affected ear(s). BC hearing aids may also
be worn in cases of single-sided deafness, wherein a BC hearing aid on the deaf side transmits the signal
through the bones and tissues of the head to the opposite (hearing) cochlea. Indeed, transcranial cross-talk is
a key feature of BC stimulation, and traditionally even in cases of bilateral conductive loss, only a single BC
device is worn. Bilateral BC stimulation results in superposition of two signals at each ear, which is expected to
limit binaural disparities and associated perceptual benefits (sound localization, speech-in-noise perception).
However, non-zero binaural disparities via bilateral BC have been reported in several biophysical studies, and
improved sound localization and speech-in-noise perception with bilateral versus unilateral BC have been
reported in several psychophysical studies. While efforts to understand and exploit binaural and spatial hearing
via BC have thus increased in recent years, basic constraints on performance remain poorly understood. The
current proposal aims to fill this knowledge gap. A first set of experiments (Aim 1) will quantify acoustic
information conveyed via bilateral BC devices using measurements of intracochlear pressure, the input drive to
the auditory system, in cadaveric specimens. A complementary set of measurements will be made during
simultaneous AC and contralateral BC stimulation, simulating the signal presented to single-sided deaf BC
hearing aid users, who show variable but generally poor outcomes in spatial tasks. A second set of
experiments (Aim 2) will determine the limits of normal-hearing psychophysical sensitivity to binaural
information conveyed via bilateral BC across key stimulus parameters, including frequency, bandwidth, and
spatial cue type. Additional measurements of BC performance in everyday spatial tasks, including sound
localization and speech-in-noise perception, will be completed and related to intracochlear and basic
psychophysical data. Collectively, the proposed experiments will evaluate the overarching hypotheses that (1)
BC signal superposition within the cochlea(e) generates systematic spatial cues, and that (2) such cues can be
used to systematically modulate perception. Data will provide critical new insi...

## Key facts

- **NIH application ID:** 10130483
- **Project number:** 5R21DC017213-03
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Andrew Dennis Brown
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $155,500
- **Award type:** 5
- **Project period:** 2019-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10130483

## Citation

> US National Institutes of Health, RePORTER application 10130483, Constraints on binaural sensitivity via bilateral bone conduction (5R21DC017213-03). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10130483. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*