Purpose
To analyze and compare the voice onset time (VOT) in Brazilian Portuguese speakers who stutter and those who do not, focusing on three different moments of speech: fluent, pre-dysfluent and post-dysfluent environments.
Methods
Twenty participants (n=10 with stuttering and n=10 without stuttering) were recorded. The data were transcribed and segmented for acoustic analysis, and it was extracted tokens of Brazilian Portuguese voiceless stops /p/, /t/ and /k/. Tokens were classified according to whether they were produced by people who stutter (PWS) or by people who do not stutter (PWnS), and according to their environment in speech (i.e., in fluent speech, pre-dysfluency, and post-dysfluency). For comparisons within groups it were used the Friedman and Wilcoxon tests, and the Mann-Whitney test was used in intergroup comparisons. Statistical analyses were executed using SPSS 14.0 with the significance level set at α=0.05.
Results
VOT in stuttering and non-stuttering speakers differed most in the environment of pre-dysfluencies, during which stuttering speakers show significantly longer VOT than speakers who do not stutter. After passing through a moment of dysfluency, however, stuttering speakers’ VOT returns to measures similar to non-stuttering speakers’.
Conclusion
In pre-dysfluent and post-dysfluent speech, PWS produces longer VOT than PWnS. In the fluent speech of PWS, the stops behave differently. The implications of these results for speech motor control are discussed.
Stuttering; Acoustics; Planning; Motor skills; Speech
