Voice onset time, frication, and aspiration during stutterers' fluent speech

The purpose of this study was to investigate voice onset time (VOT) and durations of frication and aspiration in stutterers' fluent speech. Broadband wound spectrograms were used to measure five adult stutterers' and five adult normally fluent controls' VOT, frication and aspiration durations during fluent productions of 18 word-initial sounds or sound clusters. Results indicate that stutterers' mean VOT for six of the 18 sounds/sound clusters (/p b br pr tw bl/) was significantly different from that of normally fluent speakers. VOT values for four of these 18 sounds/sound clusters (/b bl p tw/) could, to a moderate degree, be predicted from knowledge of whether a subject is a stutterer or a normally fluent speaker. With one exception, aspiration duration for /tw/, stutterers were not significantly different from normally fluent speakers in terms of frication and aspiration durations. These results suggest that stutterers' VOT during fluency is within normal limits and as such is of small assitance in distinguishing between stutterers and normally fluent speakers.