Measuring the effects of reverberation and noise on sentence intelligibility for hearing-impaired listeners

Abstract

Purpose: The Speech Transmission Index (STI; Houtgast, Steeneken, & Plomp, 1980; Steeneken & Houtgast, 1980) is commonly used to quantify the adverse effects of reverberation and stationary noise on speech intelligibility for normal-hearing listeners. Duquesnoy and Plomp (1980) showed that the STI can be applied for presbycusic listeners, relating speech reception thresholds (SRTs) in various reverberant conditions to a fixed, subject-dependent STI value. The current study aims at extending their results to a wider range of hearing-impaired listeners.

Method: A reverberant analogue of the SRT is presented--the speech reception reverberation threshold (SRRT)--which determines the amount of reverberation that a listener can sustain to understand 50% of the presented sentences. SRTs are performed and evaluated in terms of STI for 5 normal-hearing participants and 36 randomly selected hearing-impaired participants.

Results: Results show that differences in STI between reverberant and noisy conditions are only small, equivalent to a change in speech-to-noise ratio < 1.3 dB.

Conclusion: The STI appears to be a convenient, single number to quantify speech reception of hearing-impaired listeners in noise and/or reverberation, regardless of the nature of the hearing loss. In future research, the SRRT may be applied to further investigate the supposed importance of cognitive processing in reverberant listening conditions.