Auditory perceptual evaluation of rhythm-manipulated and resynthesized sentence utterances obtained from cerebellar patients and normal speakers: A preliminary report

Abstract

Alterations of the temporal structure of spoken utterances in terms of lengthened acoustic segments and increased syllabic isochrony seem to represent a salient feature of ataxic dysarthria. The present study addresses the question of whether systematic manipulations of the durational aspects of the acoustic speech signal yield an improvement of perceived dysarthric deficits. Different variants of speech rhythm were imposed on sentence utterances obtained from two patients with ataxic dysarthria and two normal control speakers. For the sake of comparability the pitch contours were standardized by means of linearly interpolated stylized versions. The introduced manipulations significantly influenced the ratings of perceived slowness, dysfluency, and rhythmic adequacy. With respect to estimates of overall intelligibility and naturalness, however, ataxic-dysarthric utterances did not benefit from any synthetic changes. By contrast, utterances of normal speakers were rated less intelligible and somewhat more unnatural when resynthesized with an ataxic rhythm. These results indicate that durational factors play a minor role with respect to the overall speech impairment of ataxic speakers.