Abstracts

Purpose: This study determined speaking rate and acoustic vowel space characteristics of young males with fragile X syndrome (FXS) as compared to typically developing males.
Method: Young males with FXS (n=38), developmental-age matched males (n=21), and chronological-age matched males (n=16) were audiotape recorded while engaged in spontaneous conversation and a picture naming task. Speaking rate in syllables-per-second, pauses that exceeded 200 ms, and vowel space area/dispersion measures were acoustically determined for each speaker.
Results: Although young males with FXS spoke significantly faster during intelligible utterances than developmental-age matched males, they did not speak faster than chronological-age matched males. Area and dispersion of the acoustic vowel space were also similar between males with FXS and chronological-age matched males. Compared to chronological-age matched males, however, young males with FXS a) used significantly shorter utterances and had a tendency to pause less often, and b) exhibited greater intra-speaker variability of vowel formants associated with /a/.
Conclusions: The findings suggest that differences in utterance length and, perhaps, pausing contribute to the perception of a fast speaking rate in young males with FXS. Intra-speaker variability of formants associated with the low vowel /a/ might reflect increased sensorimotor instability of the jaw in young males with FXS.