PURPOSE: this study aims to assess vocal deviation in individuals with developmental stuttering. METHODS: 23 adults, 9 females and 14 males, with different degrees of stuttering (Yowa Severity Scale) mean age: 31.2 years, ranging from 23 to 45, took part in the study. Perceptual auditory analysis of vocal quality was assessed by means of GIRBAS scale, with the inclusion of extra features; selected acoustic parameters were extracted. RESULTS: vocal quality was deviated in 13% of sustained vowels samples; instability was the most prominent parameter (69.57% mild and 20% moderate deviation), followed by roughness (48.70% mild and 11.30% moderate). For connected speech, roughness was the most altered parameter (59.13% mild and 1.74% moderate), followed by inconsistent tension (46.08% mild and 3.49% moderate). The maximum phonation time measurements were variable both intra and inter-subjects. The spectrographic trace showed instability due to the presence of voice breaks (21.74%), sub-harmonics (30.43%), variable fundamental frequency (8.7%) and/or vocal quality (8.7%). Perturbation measures showed to be deviated, for both shimmer (91.30%) and jitter (34,78%). CONCLUSIONS: vocal deviations are mild in stutters, evidenced at the sustained vowel task, independently of the stuttering degree. Data suggest a phonatory system's neuromotor instability in stutters.
Voice; Stuttering; Speech Acoustics; Phonation; Auditory Perception
