The phonatory function following laser surgery for glottic Tia carcinoma was investigated with 17 subjects. It was compared with the function following radiotherapy. studied in 14 subjects. The phonatory function following laser surgery for glottic T1b carcinoma was investigated with 10 subjects. It was compared with the function following radiotherapy studied in 6 subjects. The phonatory function was evaluated by (1) measuring maximum phonation time, airflow rate, fundamental frequency range, intensity range and phonatory efficiency,(2) stroboscopic examination,(3) psychoacoustic evaluation and (4) sound spectrography. The results are summarized as follows: A glottic T1a 1) The intensity of phonation during airflow measurement was louder following radiotherapy than following laser surgery. 2) The phonatory efficiency(ε) following radiotherapy was more greater than that following laser surgery. 3) The relative level of higher harmonic components was smaller following radiotherapy than following laser surgery. 4) Following laser surgery, the amplitude of vocal fold vibration was small or zero and there was little mucosal wave during vibration. 5) An incomplete glottal closure during vibration was found more frequently after laser surgery than after radiotherapy. 6) There were no significant differences in maximum phonation time, mean airflow rate, fundamental frequency range of phonation and intensity range of phonation between laser surgery and radiotherapy. B glottic T1b There were no significant differences in any test values between laser surgery and radiotherapy.
