Comparison of Voice Onset Time in People with Spastic Dysarthria and Healthy Group

Given the role of voice onset time in speech production and its value in the identification of speech disorders, the present paper aimed at comparing VOT in people with multiple sclerosis and healthy group and investigating the factors affecting VOT.

In this cross-sectional analysis study, 36 patients with MS with spastic dysarthria and 36 healthy subjects were investigated. After placing the subjects in an acoustic environment, the acoustic signal of the voiced and voiceless stop words /p/, /t/, /k/, /b/, /d/, /g/ with the vowel /a/, in the tissue cvc was recorded using the Sure-beta54 microphone. The spectrogram of the words was checked with the Praat version 6.0.36. Data were analyzed by the Shapiro-Wilk test, Independent t-test, and two-way analysis of variance.

Patients with MS have a longer VOT than healthy people, although the difference is not statistically significant (P > 0.05). The study of the effect of place of articulation on VOT revealed that the place of articulation was effective on the VOT in the healthy controls, however, there was no significant difference in the patient group. There was a significant difference in the effect of voicedvoiceless words on VOT (P < 0.05). The place of articulation and voiced-voiceless variables do not affect the voice onset time simultaneously; however, they might be effective independently (P > 0.05).

Patients with MS differ in their motor coordination between articulator structures and speech structure compared to the healthy group. Deficient speech production timing causes problems in speech motor control and ultimately changes the speech of the affected people.