Intelligibility of Reverberant Speech with Amplification: Limitation of Speech Intelligibility Metrics, and a Preliminary Examination of an Alternative Approach

Doheon Lee,Manuj Yadav,Eunju Gong,Densil Cabrera,William L Martens

doi:10.4236/jamp.2015.32028

Doheon Lee, Manuj Yadav + Show 3 more

Open Access

https://doi.org/10.4236/jamp.2015.32028

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Abstract

This study examines the effect of speech level on intelligibility in different reverberation conditions, and explores the potential of loudness-based reverberation parameters proposed by Lee et al. [J. Acoust. Soc. Am., 131(2), 1194-1205 (2012)] to explain the effect of speech level on intelligibility in various reverberation conditions. Listening experiments were performed with three speech levels (LAeq of 55 dB, 65 dB and 75 dB) and three reverberation conditions (T20 of 1.0 s, 1.9 s and 4.0 s), and subjects listened to speech stimuli through headphones. Collected subjective data were compared with two conventional speech intelligibility parameters (Speech Intelligibility Index and Speech Transmission Index) and two loudness-based reverberation parameters (EDTN and TN). Results reveal that the effect of speech level on intelligibility changes with a room’s reverberation conditions, and that increased level results in reduced intelligibility in highly reverberant conditions. EDTN and TN explain this finding better than do STI and SII, because they consider many psychoacoustic phenomena important for the modeling of the effect of speech level varying with reverberation.

Highlights

Speech intelligibility measurements are considered to be important in establishing acoustical performance for public buildings, as most of them are intended for speech communication rather than music performance
While a room’s reverberation condition and background noise are known to be the two most important factors governing speech intelligibility, the present study investigates the effect of speech level on intelligibility in various reverberation conditions—which is relevant to practical situations in which amplification is used
In an effort to better explain the results, this study explores the potential of psychoacoustic parameters to explain how speech level in conjunction with a room’ reverberation condition affects intelligibility

Summary

Introduction

Speech intelligibility measurements are considered to be important in establishing acoustical performance for public buildings, as most of them are intended for speech communication rather than music performance. Buildings and rooms may require a different degree of speech intelligibility depending on their intended use. For speech intelligibility to match the intended use of a room, it is important to accurately estimate or predict intelligibility at the design stage. While a room’s reverberation condition and background noise are known to be the two most important factors governing speech intelligibility (at a given speaker-to-listener distance), the present study investigates the effect of speech level on intelligibility in various reverberation conditions—which is relevant to practical situations in which amplification is used. In an effort to better explain the results, this study explores the potential of psychoacoustic parameters to explain how speech level in conjunction with a room’ reverberation condition affects intelligibility

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