Acoustic evaluation of Isshiki type III thyroplasty for treatment of mutational voice disorders.

The goal of this study was to determine if there are acoustical differences between pre- and post-surgical voices and to evaluate the effectiveness of Isshiki type III thyroplasty in 11 male patients with mutational voice disorders. Acoustic measures were obtained both pre- and post-operatively. A comparison of pre- and post-operative fundamental frequency (Fo), voice frequencies, and vocal intensity obtained from a sustained vowel /i/ during different phonatory tasks was made. The results from the present study demonstrated that after operation the voice frequencies were significantly decreased (p < 0.05). The vocal intensity tended to reduce slightly as the voice frequency lowered. However, there were no statistically significant differences in the pre- and post-operative measures of vocal intensity (p > 0.5). The pre-operative high pitched voices of all the male patients were lowered up to the normal value by the type III thyroplasty.