# Frequency mismatch and spectral integration in acoustic and electric hearing

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2021 · $450,054

## Abstract

SUMMARY: Bilateral cochlear implant (CI) patients and CI patients with single-sided deafness (SSD) must
integrate spectral patterns that might be quite different across ears. Due to interactions between the acoustic-
to-electric frequency allocation and the limited extent/insertion depth of the electrode array, CI patients may
experience an intra-aural mismatch between the acoustic input frequency and the electrode place within an
implanted ear. Bilateral and SSD CI patients may also experience inter-aural mismatch between the
frequency-place allocation in each, which may limit binaural benefits for speech and localization. Radiological
imaging can estimate electrode positions within the cochlea, but cannot characterize the electrode-neural
interface (the proximity of healthy neurons to the electrode), which is the ultimate arbiter of frequency
mismatch. Single-channel inter-aural pitch-matching may not fully characterize the effects of mismatch for
multi-channel speech perception. Given its additive properties, using band-limited, non-redundant speech
(rather than broadband speech) may provide greater insight regarding the effects of frequency mismatch on
spectral integration. Optimal bandwidths and frequency ranges for non-redundant speech may be estimated
from frequency importance functions.
 The long-term goal of this proposal is to better understand how frequency mismatch affects spectral
integration within and across ears. It is hypothesized that frequency importance functions may be quite
different between CI and normal-hearing (NH) listeners, and may be affected by frequency mismatch. It is
also hypothesized that the effects of frequency mismatch on spectral integration can be better estimated in
noise using band-limited, non-redundant speech. Finally, it is hypothesized that the degree of inter-aural
mismatch in CI patients can be accurately and efficiently estimated using complementary, non-redundant
speech information presented to each ear. Three aims are proposed to better explore how spectral
integration is affected by frequency mismatch. Aim 1 will explore how frequency mismatch affects the
frequency importance function for speech intelligibility. Aim 2 will explore how frequency mismatch affects
spectral integration within and across ears in NH subjects listening to unilateral, bilateral, and SSD CI
simulations, and further evaluate a novel technique to estimate inter-aural mismatch by delivering,
complementary, band-limited, non-redundant speech cues to each ear. Aim 3 will use the above novel
technique to estimate inter-aural mismatch in real CI patients and further optimize the frequency allocation
to reduce inter-aural mismatch. The proposed research is of great theoretical interest, as it will provide
greater insights into factors that limit binaural integration in bilateral and SSD CI patients. The proposed
research is also of great clinical value, as the results may provide useful clinical tools to accurately and
efficiently...

## Key facts

- **NIH application ID:** 10151596
- **Project number:** 5R01DC017738-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Qian-Jie Fu
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $450,054
- **Award type:** 5
- **Project period:** 2019-05-10 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10151596

## Citation

> US National Institutes of Health, RePORTER application 10151596, Frequency mismatch and spectral integration in acoustic and electric hearing (5R01DC017738-03). Retrieved via AI Analytics 2026-06-11 from https://api.ai-analytics.org/grant/nih/10151596. Licensed CC0.

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