[Quantitatively study of voice onset time-Glottal stop]

Area of Science:

• Speech-Language Pathology
• Acoustic Phonetics
• Craniofacial Anomalies

Background:

• Glottal stops and voice onset time (VOT) are crucial acoustic features in speech.
• Cleft palate can significantly impact speech sound production and intelligibility.
• Quantitative acoustic analysis provides objective measures of speech deviations.

Purpose of the Study:

• To quantitatively evaluate the acoustic characteristics of glottal stop pronunciation in individuals with cleft palates.
• To compare the voice onset time (VOT) of the /ka/ sound in normal subjects and patients with cleft palates.
• To investigate the relationship between VOT and psycho-acoustic judgments of speech distortion.

Main Methods:

• Sound spectrography was employed for detailed acoustic analysis.
• The pronunciation of /ka/ was analyzed in 10 normal subjects and 14 patients with cleft palates.
• Voice onset time (VOT) was measured for each subject group.

Main Results:

• Normal articulation of /ka/ showed an average VOT of 44.6 msec.
• Patients with cleft palates demonstrated a significantly shorter average VOT of 20.8 msec for /ka/.
• A significant inverse correlation was found between VOT and the perceived degree of speech distortion.

Conclusions:

• Patients with cleft palates exhibit altered acoustic characteristics in their speech, specifically a reduced VOT.
• Shorter VOT in cleft palate speakers is associated with increased psycho-acoustic perception of speech distortion.
• Acoustic analysis, particularly VOT measurement, can aid in understanding and quantifying speech impairments in cleft palate populations.