Acoustic Analysis of Dysarthria: A Comparative Study with Healthy Controls

Plosive sounds involve complex coordination among anatomical structures, including the respiratory system, larynx, and supra-laryngeal structures, often resulting in divergent acoustic measurements in individuals with speech-language disorders. Dysarthria, characterized by impaired speech motor control, significantly affects speech articulation. This study, conducted in Islamabad, Pakistan, explores Voice Onset Time (VOT) in dysarthric individuals compared to healthy controls. Thirty participants, 15 with dysarthria and 15 age-matched healthy speakers, were recruited from the National Institute of Rehabilitation Medicine and the Armed Forces Institute of Rehabilitation Medicine, based in Islamabad. Employing a quantitative design, acoustic analysis was performed using PRAAT (v5.3.56), and statistical analysis was conducted using SPSS (v21). This study offers a novel contribution by analyzing VOT variations in a linguistically diverse population across different types of dysarthria, including Urdu, Punjabi, and Balti speakers. Results indicated that dysarthric speakers had consistently longer VOT values, with a mean difference of -33.52 milliseconds (dysarthric) compared to -18.74 milliseconds (healthy), a statistically significant gap (p < 0.05). Voiced/voiceless distinctions and place of articulation were identified as factors influencing VOT in both groups. The findings provide strong evidence of prolonged VOT in dysarthric speech, emphasizing the relationship between speech motor control deficits and phonetic features. Future research could benefit from longitudinal studies tracking changes in VOT over time, offering insights into the progression of dysarthria and aiding the development of more targeted therapeutic interventions.