Articulation rate and vowel space characteristics of young males with fragile X syndrome: preliminary acoustic findings.

Purpose: Increased speaking rate is a commonly reported perceptual characteristic among males with fragile X syndrome (FXS). The objective of this preliminary study was to determine articulation rate-one component of perceived speaking rate-and vowel space characteristics of young males with FX5. Method: Young males with FX5 (n = 38), developmental age (DA)-matched males, (n = 21), and chronological age (CA)-matched males (n = 16) were audiotaped while engaged in spontaneous conversation and a picture-naming task. Articulation rate in syllables per second during intelligible utterances and vowel space area/dispersion measures were acoustically determined for each speaker. Results: Males with FX5 did not articulate significantly faster than CA-matched males. Area and dispersion of the acoustic vowel space also were similar between the 2 groups. Males with FX5, however, used significantly shorter utterances and had a tendency to pause less often than CA-matched males. In addition, males with FX5 exhibited greater intraspeaker variability of formants associated with the vowel /a/. Conclusions: These preliminary findings suggest that articulation rate may not be a primary factor contributing to perceived speaking rate of males with FXS. Limitations of the study relative to speech production tasks and utterance intelligibility are discussed.