Speech rate according to stuttering severity

Speech duration has been the subject of acoustic studies due to its relationship with rhythm and speech rate. The speech analysis of stutterers has revealed data which often differs from that found in non-stutterers. These differences most likely stem from timing disturbances related to speech motor control.

To compare the speech rates of individuals presenting different stuttering severity levels.

Participants were 6 adult stutterers with the following severity levels: 2 with mild stuttering; 2 with moderate stuttering and 2 with severe stuttering. The words 'cavalo' (horse), 'pipoca' (popcorn) and 'tapete' (carpet) were introduced in a carrier phrase, 'Digo......baixinho' (Say ......in a low voice). Each phrase was uttered by the researcher and then repeated aloud 3 times by the participants while being recorded in a computer. Utterances containing speech disruptions were discarded. Subsequently, timing measurements were made, using the Praat 4.2 software. Utterances were divided into segments delimited by two consecutive voice onsets, and speech rate was then calculated (number of vowel-vowel segments divided by the total sum of duration of the segments). The data were analyzed statistically using ANOVA.

The group with mild/moderate stuttering presented higher and similar speech rates, differing statistically from the group with severe stuttering, therefore indicating that the higher the severity of stuttering, the lower the speech rate. This difference seems to be related to difficulties in motor programming, affecting mainly the rhythm and the timing of discourse.

The rate of fluent speech during a repetition task differentiated the studied individuals according to the severity of stuttering.