Characteristics of Speech and Voice as Predictors of the Quality of Communication in Adults with Hypokinetic Dysarthria

Hypokinetic dysarthria is characterized by a speech that gradually becomes monotonous, poorly modulated, quiet and ultimately unintelligible. The goal of this research is to determine the acoustic characteristics of voice and speech in adults with hypokinetic dysarthria and the impact of the altered voice on the quality of communication. The sample consisted of 30 elderly respondents of both genders with Parkinson’s disease and hypokinetic dysarthria. In order to conduct a spectral analysis, the voice of patients was recorded while they were reading phonetically balanced text. The respondents conducted a self-assessment of the degree of their own handicap caused by voice disorder and impact of the voice handicap by completing the Voice Handicap Index (VHI). Statistically significant differences were determined in the position of some formants in respondents compared to the values of formants in typical speakers for the following vowels: F1 of the vowel /I/ and F2 of the vowels /E/, /I/, /O/ and /U/. By examining the relation between the score achieved on the VHI instrument and the value of formants, the only statistically significant correlation was achieved between the formant F1 of the vowel /A/ and functional and emotional subscale. By regression analysis used to determine the predictor of the quality of communication, it was confirmed that F1 of the vowel /A/ has a statistically significant contribution to the explanation of the score achieved on functional and emotional subscale, by explaining 15% of the functional subscale (Beta=-0,393 (11,30 – 47,37)) and 10% of the emotional subscale (Beta=-0,363 (-0,052 – 0,000)).