Phonatory volume velocity recording by use of hot film anemometry and signal analysis

Phonatory airflow volume velocity signal was recorded from nine normal adult males and eight hoarse patients with laryngeal carcinoma; hot film anemometry and computer-aided signal analysis were used. Marked differences in phonatory flow signal were seen in the two groups. The normal phonatory flow signal is quasiperiodic, with excellent cycle-to-cycle repetition at the frequency of vocal fold vibration. The signal's spectral energy is dominated by the fundamental and its harmonics. The phonatory flow signal in cancer is characterized by random and aperiodic fluctuations. There is decreased AC-to-DC signal ratio. The phonatory signal spectra reveal little harmonic power. The loss of periodic flow signal is consistent with clinical observation of aperiodic vocal fold vibration in cancer. The analysis of airflow signal is a potentially valuable method for monitoring airflow during phonation in conditions affecting the larynx.