Analysis of stutterers' voice onset times and fundamental frequency contours during fluency

The purpose of this study was to examine stutterers' and nonstutterers' fluent voice onset time (VOT) and fundamental frequency (Fo) contour measures from target syllables located at the beginning of a carrier phrase. Ten adult male stutterers were matched within one year of age with 10 adult male nonstutterers. Oscillographic and spectrographic analyses of subjects' VOT and Fo at vowel onset, average vowel Fo, and speed and range of Fo change were obtained from fluent productions of 18 stop consonant-vowel syllables. Results showed that VOTs for voiced stops and the range of Fo change for voiceless stops were associated with significant between-group differences. All other dependent measures were not significantly different between the two groups. When compared with past research, these findings indicate that greater differences emerge between stutterers and nonstutterers when measures of fluency are taken at the beginning than in the middle of a carrier phrase. Implications for future research are discussed.