Factors influencing intelligibility and fluency in non-native speech

Abstract

Substantial research has examined the factors making non-native speech more difficult to understand than native speech. Prior work has suggested that speaking rate is one such factor, with slower speech being perceived as less comprehensible and more accented. Further, non-native speech is produced with shorter utterances and more frequent pauses than native speech. Recent work has suggested that in addition to non-native speech being produced more slowly than native speech, it is produced with a more variable speaking rate. In the present study, we examine the relationship between variability in speaking rate, pausing and utterance length, and intelligibility and fluency ratings of non-native speech. We asked listeners to transcribe sentences produced by non-native speakers and to rate the fluency of read speech. Preliminary results suggest that rate variability does correlate with intelligibility of non-native speech, but not of native speech, and rate variability does not correlate as strongly with fluency. In addition, pause duration may interact with sentence complexity, but appears independent of rate. These results suggest that while fluency and intelligibility are abstract constructs, examining variability in non-native speech and its relationship to a number of factors may help explain why non-native speech is difficult to understand.