Electro-haptic enhancement of speech-in-noise performance in cochlear implant users

Mark D Fletcher,Tobias Goehring,Sean R Mills,Amatullah Hadeedi

doi:10.1038/s41598-019-47718-z

Abstract

Cochlear implant (CI) users receive only limited sound information through their implant, which means that they struggle to understand speech in noisy environments. Recent work has suggested that combining the electrical signal from the CI with a haptic signal that provides crucial missing sound information (“electro-haptic stimulation”; EHS) could improve speech-in-noise performance. The aim of the current study was to test whether EHS could enhance speech-in-noise performance in CI users using: (1) a tactile signal derived using an algorithm that could be applied in real time, (2) a stimulation site appropriate for a real-world application, and (3) a tactile signal that could readily be produced by a compact, portable device. We measured speech intelligibility in multi-talker noise with and without vibro-tactile stimulation of the wrist in CI users, before and after a short training regime. No effect of EHS was found before training, but after training EHS was found to improve the number of words correctly identified by an average of 8.3%-points, with some users improving by more than 20%-points. Our approach could offer an inexpensive and non-invasive means of improving speech-in-noise performance in CI users.

Highlights

When a sense is impaired or abolished, the brain adapts, relying more heavily on other senses to extract information[1,2]
Tactile stimulation increased the number of words correctly identified by 8.3%-points on average compared to audio alone, with some individuals improving by more than 20%-points and no individuals decreasing in performance. This benefit was observed for speech in multi-talker noise, where Cochlear implant (CI) users are known to struggle most[19,20], and in which noise reduction algorithms typically perform poorly[21,22]
The tactile signal was delivered at an intensity that could readily be produced by a low-cost wearable device after computationally non-intensive signal processing suitable for a real-time application

Summary

Introduction

When a sense is impaired or abolished, the brain adapts, relying more heavily on other senses to extract information[1,2]. Results from previous studies suggest that speech amplitude envelope information is a crucial missing feature for CI users listening in noise[5,6]. Given the brain’s ability to extract missing information through another sense, speech-in-noise performance in CI users may be improved by providing speech envelope information through tactile stimulation. This haptic augmentation of the electrical signal from the CI will be referred to as “electro-haptic stimulation” (EHS). Fletcher et al.[16] found that tactile presentation of speech envelope improved speech intelligibility for normal-hearing subjects listening to CI simulations (NHCIs)[16]. After training, EHS will increase the percentage of keywords in noise that CI users are able to correctly identify

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Results

Conclusion