Temporal Processing and Speech Perception in Noise by Listeners with Auditory Neuropathy

Vijaya Kumar Narne,Claude Alain

doi:10.1371/journal.pone.0055995

Vijaya Kumar Narne, Claude Alain

Open Access

https://doi.org/10.1371/journal.pone.0055995

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Abstract

AimThe present study evaluated the relation between speech perception in the presence of background noise and temporal processing ability in listeners with Auditory Neuropathy (AN).MethodThe study included two experiments. In the first experiment, temporal resolution of listeners with normal hearing and those with AN was evaluated using measures of temporal modulation transfer function and frequency modulation detection at modulation rates of 2 and 10 Hz. In the second experiment, speech perception in quiet and noise was evaluated at three signal to noise ratios (SNR) (0, 5, and 10 dB).ResultsResults demonstrated that listeners with AN performed significantly poorer than normal hearing listeners in both amplitude modulation and frequency modulation detection, indicating significant impairment in extracting envelope as well as fine structure cues from the signal. Furthermore, there was significant correlation seen between measures of temporal resolution and speech perception in noise.ConclusionResults suggested that an impaired ability to efficiently process envelope and fine structure cues of the speech signal may be the cause of the extreme difficulties faced during speech perception in noise by listeners with AN.

Highlights

Auditory Neuropathy (AN) is a term used to describe auditory disorders with dysfunction of the auditory nerve in the presence of preserved cochlear outer hair-cell function [1,2]
Results demonstrated that listeners with AN performed significantly poorer than normal hearing listeners in both amplitude modulation and frequency modulation detection, indicating significant impairment in extracting envelope as well as fine structure cues from the signal
Multi-factorial regression analysis showed that impaired ability to follow amplitude variations accounts majorly for impaired speech perception in quiet, whereas speech perception difficulties in noise were accounted by impaired ability to follow amplitude and frequency variations in speech signal

Summary

Introduction

Auditory Neuropathy (AN) is a term used to describe auditory disorders with dysfunction of the auditory nerve in the presence of preserved cochlear outer hair-cell function [1,2]. Listeners with cochlear hearing loss have difficulty in understanding speech in quiet, more so in the presence of competing signals [5]. Attempts have been made through psychoacoustic and simulation studies to explain factors responsible for perceptual difficulties experienced by listeners with AN in quiet [8,9,10]. These investigators have suggested that perceptual difficulties experienced by listeners with AN may be due to an impaired ability to follow amplitude variations in speech signals (temporal envelope cues). It has been hypothesized that this impaired ability to follow amplitude variations may reduce the consonant-vowel distinction, resulting in extreme difficulty in understanding speech [9]

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