Voice Onset Time Variations of Korean Stop Consonants in Aphasic Speakers

OBJECTIVE To compare the voice onset time (VOT) differences of Korean stops in the initial and intervocalic positions between the aphasic patients with peculiarities of aspiration and a control group. METHOD We examined 15 aphasic patients (nine males, six females) who had suffered a stroke (average age 49.7 years) and 15 healthy controls (average age 47.4 years). An aphasia examination was made by an aphasia battery of three standard tests and VOT was analyzed instrumentally. Stop consonants in the initial and intervocalic position were measured to categorize them according to aphasia types, place of articulation, and manner of articulation. RESULTS VOT of the aphasic patients with peculiarities of aspiration had a greater difference than that of the controls, indicating that the temporal non-coordination between the laryngeal adjustment and oral articulators of aphasic patients happens due to the VOT of stops in the initial and intervocalic positions (p<0.05). CONCLUSION VOT of stop consonants in the initial position produced by aphasic patients tends to be proportional to their breathing. It can cause glottal width and make aphasic patients' VOT duration longer. Lastly, the method to measure the VOT of aphasic patients is more significant for the types of phonation than for the places of articulation, and makes it possible to induce abnormal VOT.