Speech intelligibility in a realistic virtual sound environment.

Naim Mansour,Tobias May,Adam Westermann,Marton Marschall,Torsten Dau

doi:10.1121/10.0004779

Abstract

In the present study, speech intelligibility was evaluated in realistic, controlled conditions. "Critical sound scenarios" were defined as acoustic scenes that hearing aid users considered important, difficult, and common through ecological momentary assessment. These sound scenarios were acquired in the real world using a spherical microphone array and reproduced inside a loudspeaker-based virtual sound environment (VSE) using Ambisonics. Speech reception thresholds (SRT) were measured for normal-hearing (NH) and hearing-impaired (HI) listeners, using sentences from the Danish hearing in noise test, spatially embedded in the acoustic background of an office meeting sound scenario. In addition, speech recognition scores (SRS) were obtained at a fixed signal-to-noise ratio (SNR) of -2.5 dB, corresponding to the median conversational SNR in the office meeting. SRTs measured in the realistic VSE-reproduced background were significantly higher for NH and HI listeners than those obtained with artificial noise presented over headphones, presumably due to an increased amount of modulation masking and a larger cognitive effort required to separate the target speech from the intelligible interferers in the realistic background. SRSs obtained at the fixed SNR in the realistic background could be used to relate the listeners' SI to the potential challenges they experience in the real world.

Highlights

Through their auditory perception, normal-hearing people are able to communicate nearly effortlessly even in challenging acoustic scenarios, such as at a social gathering or in a busy restaurant
Speech reception thresholds (SRT) in the artificial noise” condition (AR) condition were significantly higher than those in the headphone condition” (HP) condition (p 1⁄4 0.034). These results demonstrate that speech intelligibility decreased (i.e., SRTs increased) in the realistic noise” condition (RE) condition compared to the HP condition in both listener groups, whereas the performance in the RE condition was much more affected in the HI listener group than in the NH listener group
The results indicate that all listeners rated the background noise in the RE condition as mostly very realistic sounding, while the HI listeners experienced the speech in the RE condition as overall more realistic and difficult to understand

Summary

Introduction

Normal-hearing people are able to communicate nearly effortlessly even in challenging acoustic scenarios, such as at a social gathering or in a busy restaurant. Despite considerable technological advances in hearing aid technology, hearing aid benefit varies greatly among individual users, in reverberant situations with multiple interfering sound sources To appreciate why this occurs, it is necessary to understand how human hearing is currently evaluated in the context of hearing aid applications. Considered paradigms, such as loudness perception or speech intelligibility, utilize well-defined, artificially created acoustic stimuli presented over headphones or small sets of loudspeakers. This approach, while having the advantage of being fully controlled and replicable, does not necessarily reflect conditions in the real world

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