Intelligibility of temporally interrupted speech

Abstract

The variations in intelligibility of a temporally interrupted connected discourse passage that result from changes in both switching conditions and message rate were studied. Six normal-hearing listeners estimated the intelligibility of ten, 15-sec speech samples presented monaurally at 36 interruption conditions (12 interruption rates × 3 speech-time fractions) for each of two speaking rates. Results indicated that for a given speech-time fraction, changes in intelligibility as a function of interruption rate depend on the precise temporal correspondence of switching and message parameters. Specifically: (1) for slow interruption rates, where on-time and off-time are greater than average word duration, temporal features of the message are relatively unimportant and intelligibility varies directly with speech-time fraction; (2) intelligibility functions will begin to recover from minimum at an interruption rate where off-time is equal to, or just shorter than, average word duration; (3) differences in performance along the recovery portions of the functions for the two message rates are negligible when intelligibility is expressed in terms of percent off-time relative to average word duration. It is apparent that a trading relation exists between speech-time fraction and interruption rate. Within certain limits, decrements resulting from lowering the speech-time fraction can be overcome by increasing the switching rate.