Loading-Related Subjective Symptoms during a Vocal Loading Test with Special Reference to Gender and Some Ergonomic Factors

Abstract

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.

Vocal Impact of a Prolonged Reading Task at Two Intensity Levels: Objective Measurements and Subjective Self-Ratings

“…Subjectively, previous studies have shown a significant increase in self-rated voice symptoms during the working day 3,6,9 or after a loading task performed in a laboratory. 10,16,17,32 Effects of intensity level as voice loading factor Voice intensity changes with the amplitude of vocal fold's oscillations, influencing the distance dose and the dissipated energy dose. 14,31 Voice intensity affects the shear stress in the ligament 33 and the medial compression of the vocal folds (compressive stress).…”

“…36 Effects of both duration and intensity level on voice Few studies have observed the effect of both intensity level and duration of the loading task. Vintturi et al 18,32 studied the changes in voice during a vocal loading test with, among others, a specific emphasis on the speech output level. Neils and Yairi 40 examined the influence of various levels and durations of noise exposure in six females reading in noise during 45 minutes.…”

The Effect of a Vocal Loading Task on Vocal Function Before and After 24 Hours of Thickened Liquid Use

“…Systemic dehydration of the body, as well as superficial dehydration of the vocal tract, such as may occur through oral breathing or conditions of low humidity, contributes to increases in perceived vocal effort [14,34,35]. This increase in perceived vocal effort is likely related to an increase in PTP [34]. As previously discussed, reduced hydration contributes to an increase in vocal fold viscosity, thus decreasing mobility and increasing the muscular effort required to phonate [13].…”

“…Systemic dehydration of the body, as well as superficial dehydration of the vocal tract, such as may occur through oral breathing or conditions of low humidity, contributes to increases in perceived vocal effort [14,34,35]. This increase in perceived vocal effort is likely related to an increase in PTP [34].…”

“…The extent to which the use of thickened liquids may affect vocal function in patients with dysphonia and/or patients with dysphagia is not known. Sivasankar and Fisher [34] demonstrated that superficial dehydration of the vocal tract in dysphonic speakers was associated with greater increases in phonatory threshold pressure in comparison to non-dysphonic speakers. They suggested that this pattern was due to a reduced ability of the dysphonic speakers to compensate for the negative effects of dehydration.…”