Cerebellar voice tremor: an acoustic analysis.

Patients with cerebellar disease may exhibit tremulous phonation as part of their dysarthria. The results of an acoustic analysis of cerebellar voice tremor in a patient with hereditary ataxia and presenting with a purely cerebellar syndrome are reported. Analysis included computation of speech intensity contours, fundamental frequency contours, and spectral parameters from sustained productions of vowels and voiceless fricatives. Fundamental frequency contours during sustained phonation of vowels showed rhythmic oscillations at a rate of about 3 Hz. No concomitant periodicity could be detected for the parameters characterising voiceless fricative production. The results indicate an impairment of phonatory control in relation to the maintenance of a constant isometric activity of the internal laryngeal muscles. Cerebellar voice tremor may therefore be classified as a form of postural tremor.