Effects of speechreading and signal-to-noise ratio on understanding mainstream American English by American and Indian adults.

Abstract

The purpose of this study was to measure effects of speechreading and signal‐to‐noise ratio (SNR) on understanding mainstream American English (MAE) heard by 30 Indian adults compared to 30 American adults. Participants listened to a recording of a female speaker of MAE saying ten lists of ten different everyday speech sentences per list. Participants heard sentences from a TV loudspeaker at a 65 dB sound pressure level, while a four‐talker babble played through two surrounding loudspeakers at various SNRs under auditory‐visual and auditory modalities. Each participant’s speechreading performance at each SNR was computed as the difference in words correctly heard through auditory‐visual versus auditory modalities. Consistent with most previous research, American participants benefited significantly more from speechreading at poorer SNRs than at favorable SNRs. The novel finding of this study, however, was that Indian participants benefited less from speechreading than American participants at poorer SNRs, but benefited more from speechreading than American participants at favorable SNRs. Linguistic (and, possibly, nonlinguistic) variables may have accounted for these findings, including an increased need for Indian participants to integrate more auditory cues with visual cues to benefit from speechreading, presumably because they only spoke English as a second language.