Eugene H. Buder
Dept. of Speech and Hear. Sci., Univ. of Washington, JG-15, 1417 NE 42nd St., Seattle, WA 98195
Edythe A. Str
Univ. of Washington
A subgroup of patients with dysarthria resulting from amyotrophic lateral sclerosis (ALS) presents with voice problems characterized primarily by cycle-to-cycle and long-term phonatory instabilities. This paper reports acoustic analyses of the phonation of a 63-yr-old female 9 months post diagnosis of ALS. Perceptual characteristics of voice included inconsistent harshness and cyclic variations in both pitch and loudness. Spectral analysis of fundamental frequency (f0) and intensity contours revealed periodic instabilities at multiple temporal domains, including 0.4- and 0.8- Hz cycles in both f0 and intensity (``wow''), 2-Hz cycles in f0 (``tremor''), and 11-Hz cycles in intensity (``flutter''). Phase relations were noted among these cycles and with other acoustic analysis parameters such as perturbation and spectral energy distribution, indicating that occurrence of short-term and cycle-to-cycle instabilities was modulated by the longer term cycles. The results are discussed with relation to video stroboscopic examinations of this patient, and also in comparison with phonatory characteristics of other patients in this subgroup (females with ALS related voice problems). [Work supported by NIH.]