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 dis orders. Acoustic measures were obtained both pre- and post-operatively. A c omparison of pre- and post-operative fundamental frequency (Fo), voice freq uencies, and vocal intensity obtained from a sustained vowel /i/ during dif ferent phonatory tasks was made. The results from the present study demonst rated that after operation the voice frequencies were significantly decreas ed (p<0.05). The vocal intensity tended to reduce slightly as the voice fre quency lowered. However, there were no statistically significant difference s in the pre- and post-operative measures of vocal intensity (p>0.5). The p reoperative high pitched voices of all the male patients were lowered up to the normal value by the type III thyroplasty.