Analysis of vocal abuse: fluctuations in phonation time and intensity in 4 groups of speakers

We have seen many patients with a voice disorder due to vocal abuse. However, there is little information about the speaking behaviour of such patients. The object of this study was to analyze speaking behaviour and to evaluate the relationship between the cause of voice disorders and its effects on speech. We had previously measured phonation time with a speech time accumulator. Recently, we have developed a speech intensity/speech time accumulator. We obtained data by accumulating the phonation time at 4 degrees of vocal intensity, ranging from weak to strong. By using this instrument, we measured the speaking habits of 29 subjects for 131 days and collected data about the criteria for vocal abuse. Our results showed that the office workers exhibited a phonation time (33.6 +/- 13.6 min for 8 h) three times shorter than that of teachers and patients with vocal fold nodules (102.1 +/- 22.9 min for 8 h). For the teachers and patients with a long phonation time, half of the total phonation time was at high intensity.