Perceptuo-acoustic assessment of prosodic impairment in dysarthria

Dysprosody was studied in four groups of male subjects: subjects with amyotrophic lateral sclerosis (ALS) and mild intelligibility impairment, subjects with ALS and a more severe intelligibility loss, subjects with cerebellar disease, and neurologically normal controls. Dysprosody was assessed with perceptual ratings and acoustic measures pertaining to the regulation of duration, f₀, and intensity within lone units of conversational samples. Intelligibility reduction and prosodic disturbance were not necessarily equally impaired in all subjects, and it is concluded that these are complementary indices of severity of dysarthria. Compared to the neurologically normal control group, the clinical groups tended to decrease the overall duration of tone units, produce fewer words in a tone unit, and use smaller variations in f₀. Recommendations are offered for the assessement of prosody in dysarthria.