The purpose of this study is to determine the acoustic characteristics of dysarthria depending upon the underlying etiology. We used sound spectrography to assess the formant characteristics. phonation time of vowel, and voice onset time of alveolar consonants. With Nasometer, we evaluated nasalance with reflects the ratio of nasal and oral acoustic energy. Visi-Pitch was also used to evaluate pitch perturbation, pitch range, and diadochokinetic rates of the articulatory organ.

Underlying etiology of dysarthria included pseudobulbar palsy in 5 patients, bulbar palsy in 2 patients, language delay in 3 patients, and tonsilar hypertrophy in 3 patients.

In spectrographic evaluation, most dysarthric patients were characterized by loss of specific characteristics of formants of vowel, increased noise in high frequency range, and reduced duration of phonation. Voice onset time was prolonged in alveolar stop consonants in dysarthric patients with pseudobulbar and bulbar palsy.

Nasalance was increased in dysarthric patients with pseudobulbar and bulbar palsy, but decreased in patients with tonsilar hypertrophy.

In Visi-Pitch analysis, voice intensity was normal in all types of dysarthria However, pitch perturbation was increased in dysarthric patients with tonsilar hypertroghy, pseudobulbar and language delay palsy. Diadochokinetic rate was decreased in all dysarthric patients.

Sound spectorgrapy. Nasometer and Visi-pitch were considered to be useful to determine the specific acoustic characteristics of dysarthria in the patients with neurological involvement and structuarl lesion, but were not sensitive to delineate the pathologie region of neurologicl involvements.