1988 Volume 29 Issue 2 Pages 161-167
We investigated the acoustic characteristics of repetition of interrupted vowel /a/ and that of syllable /pa/ in three groups each containing six subjects: namely, spastic dysarthrics, ataxic dysarthrics and normal controls. The results were as follows: (1) spastic and ataxic subjects showed remarkable reduction in number of repetitions in both tasks: (2) spastic subjects demonstrated longer mean voiced duration in repetition of interrupted vowel /a/ than in repetition of syllable /pa/, while in ataxic subjects the proportion of the voiced duration in /a/ to that in /pa/ was as normal as seen in the control group; and (3) in spastic subjects, the coefficient of variation of the peak value in repetition of syllable /pa/ was as large as seen in ataxic subjects, while the coefficient of variation of the peak value in repetiton of the interrupted vowel /a/ was similar to that of normal subjects, although it remained larger in ataxic subjects.
These results, particularly (2) and (3), suggested that the vocal characteristics, as derived from biased hypertonus of the laryngeal muscles, could be reflected in the“on-off phonation test.”
