Loading-related subjective symptoms during a vocal loading test with special reference to gender and some ergonomic factors.

Vocal loading-related subjective symptoms were studied in a day-long vocal loading test. The voices of 40 female and 40 male voluntary young students were loaded by having them read aloud a novel for five times 45 min. The subjective symptoms that occurred during the vocal loading session were reported by filling in a questionnaire after each session. The responses loaded on five factors in a factor analysis: (1) 'central fatigue'; (2) 'symptoms of the neck, shoulders and back'; (3) 'drying in the mouth and throat'; (4) 'symptoms of the throat'; (5) 'symptoms of the voice'. The exposure groups (5 females and 5 males per cell) consisted of eight combinations of the following factors: (1) low (25 +/- 5%) or high (65 +/- 5%) relative humidity of ambient air; (2) low [<65 dB(SPL)] or high [>65 dB(SPL)] speech output level of vocal loading; (3) sitting or standing posture during vocal loading. The lowest mean score for symptoms pooled over the test were found in 'symptoms of the neck, shoulders and back' and the highest mean symptom score in 'drying in the mouth and throat' and 'symptoms of the throat'. Most symptoms were at their minimum during the first loading session and increased statistically significantly to a peak mean value after three or five vocal loading sessions. Statistically significant differences in the mean level between the gender or exposure groups emerged for 'central fatigue' (humidity had clear effects) and 'symptoms of the neck, shoulders and back' (gender, humidity and posture had clear effects). In these cases, females had more symptoms than males; the low-humidity group had more symptoms than the high-humidity group, and the standing subjects had more symptoms than the sitting subjects. Copyright 2003 S. Karger AG, Basel