Lexical tone and stuttering loci in Mandarin: evidence from preschool children who stutter.

The purpose of this study was to examine the relationship between stuttering loci and lexical tone in Mandarin-speaking preschoolers. Conversational samples from 20 Taiwanese children who stutter (CWS; M = 4:9; range = 3:2-6:4) were analysed for frequency and type of speech disfluency and lexical tone associated with stuttering-like disfluencies (SLDs). Results indicated that SLDs were significantly more likely to be produced on Mandarin syllables carrying Tone 3 and Tone 4 syllables compared to syllables carrying either Tone 1 or Tone 2. Post-hoc analyses revealed: (1) no significant differences in the stuttering frequencies between Tone 1 and Tone 2, or between Tone 3 and Tone 4, and (2) a higher incidence of stuttering on syllables carrying Tone 3 and Tone 4 embedded in conflicting (as opposed to compatible) tonal contexts. Results suggest that the higher incidence of stuttering on Mandarin syllables carrying either Tone 3 or 4 may be attributed to the increased level of speech motor demand underlying rapid F0 change both within and across syllables.