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Publication . Article . 2018

Coherent Coding of Enhanced Interaural Cues Improves Sound Localization in Noise With Bilateral Cochlear Implants.

Open Access
Published: 01 Jan 2018 Journal: Trends in Hearing (issn: 2331-2165, Copyright policy )
Abstract

Bilateral cochlear implant (BCI) users only have very limited spatial hearing abilities. Speech coding strategies transmit interaural level differences (ILDs) but in a distorted manner. Interaural time difference (ITD) information transmission is even more limited. With these cues, most BCI users can coarsely localize a single source in quiet, but performance quickly declines in the presence of other sound. This proof-of-concept study presents a novel signal processing algorithm specific for BCIs, with the aim to improve sound localization in noise. The core part of the BCI algorithm duplicates a monophonic electrode pulse pattern and applies quasistationary natural or artificial ITDs or ILDs based on the estimated direction of the dominant source. Three experiments were conducted to evaluate different algorithm variants: Experiment 1 tested if ITD transmission alone enables BCI subjects to lateralize speech. Results showed that six out of nine BCI subjects were able to lateralize intelligible speech in quiet solely based on ITDs. Experiments 2 and 3 assessed azimuthal angle discrimination in noise with natural or modified ILDs and ITDs. Angle discrimination for frontal locations was possible with all variants, including the pure ITD case, but for lateral reference angles, it was only possible with a linearized ILD mapping. Speech intelligibility in noise, limitations, and challenges of this interaural cue transmission approach are discussed alongside suggestions for modifying and further improving the BCI algorithm.

Subjects by Vocabulary

Microsoft Academic Graph classification: Speech coding Coding (social sciences) QUIET Speech recognition Interaural time difference Cochlear implant medicine.medical_treatment medicine Sound localization Speech perception Brain–computer interface Computer science

Subjects

Speech and Hearing, Otorhinolaryngology

Funded by
EC| IBiDT
Project
IBiDT
Individualized Binaural Diagnostics and Technology
  • Funder: European Commission (EC)
  • Project Code: 716800
  • Funding stream: H2020 | ERC | ERC-STG
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Trends in Hearing
Article
License: cc-by-nc
Providers: UnpayWall
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