Acoustic analysis of pathological voice. Some results of clinical application

Tape-recorded voices of 30 patients were acoustically analysed: 10 had glottic Tla carcinoma, 10 unilateral vocal fold polyp and 10 unilateral recurrent laryngeal nerve paralysis. The carcinoma cases were treated with laser surgery with/without radiotherapy, the polyp cases with endolaryngeal microsurgery and the paralysis cases with intrafold silicone injection. The acoustic analysis was conducted before and after the treatment for each patient. Three acoustic parameters, viz. pitch perturbation quotient (PPQ), amplitude perturbation quotient (APQ) and normalized noise energy (NNE), were employed. The results were as follows: (1) PPQ and APQ were greater in paralysis cases than in carcinoma and polyp cases; (2) none of the parameters was useful in differentiating the three disease groups investigated; (3) all three parameters proved to be useful in monitoring the effects of treatments; (4) all three parameters were positively correlated to the grade of hoarseness, rough and breathy quality of hoarseness, mean airflow rate and regularity of vocal fold vibration viewed under stroboscopy; (5) PPQ, APQ and NNE were positively related to each other.