Quantitative Analysis of Voice Quality after Radiation Therapy for Stage T1a Glottic Carcinoma

Purpose: To evaluate the voices of irradiated patients with early glottic carcinoma and to compare these with the voices of healthy volunteers. Material and methods: The voice samples (sustained vowel) of seventeen male patients who had been irradiated for T1a glottic squamous carcinoma at least 1 year prior to the study were analyzed with objective voice analyzer (acoustic voice analysis, aerodynamic test, and videostroboscopic analysis) and compared with those of a normal group of twenty age-and sex-matched volunteers. Average fundamental frequency, jitter, shimmer, and noise-to-harmonic ratio were obtained for acoustic voice analysis. Maximal phonation time, mean flow rate, intensity, subglottic pressure, glottal resistance, glottal efficiency, and glottal power were obtained for aerodynamic test. Results: The irradiated group presented higher values of shimmer in acoustic voice analysis. There was no significant difference between two groups in other parameters. Conclusion: In this study all the objective voice parameters except shimmer were not significantly different between the irradiated group and the control group. These results suggest that the voice quality is minimally affected by radiation therapy for T1a glottic carcinoma.