Fundamental frequency, sound pressure level and vocal dose of a vocal loading test in comparison to a real teaching situation

Abstract

Vocal loading capacity is an important aspect of vocal health, especially for people in vocally demanding occupations such as teaching. To analyze vocal loading, vocal loading tests (VLTs) or portable voice devices such as accelerometers have been used. However, it remains unclear how much a VLT in a clinical setup reflects the vocal effort of a real situation, in particular for teachers in a given classroom lesson. In this study of vocally healthy 101 student teachers, we analyzed different vocal doses for a 10-min VLT (80 dB at a distance of 30 cm) and a real 45-min teaching lesson. The phonation time, fundamental frequency, sound pressure level, and noise level were recorded using the VoxLog accelerometer/microphone system for both conditions. From these measurements the time dose, cycle dose, distance dose, energy dissipation dose, and radiated energy dose were calculated. The VLT was associated with a higher fundamental frequency, a higher sound pressure level, and higher relative phonation time compared to the real teaching lesson. Nevertheless, most vocal doses did not differ significantly between the conditions. A VLT of 10 min with >80 dB at 30 cm distance shows only small differences of vocal doses in comparison to a real teaching situation of 45 min. Thus, for clinical vocal assessment the vocal load of a VLT can be related to an approximately 45-min teaching situation.

Investigation of Vocal Fatigue Using a Dose-Based Vocal Loading Task

“…An abrupt increase in vocal loading was closely related to a harsher subjective self-reported rating [30]. Echternach et al found that a 10-min intensive VLT with a >80 dB loudness level was comparable to a 45-min teaching task in terms of vocal dose [31]. Remacle et al showed that kindergarden teachers had significantly greater distance doses than elementary school teachers based on an investigation of 12 kinderdarten and 20 elementary school female teachers [5].…”

Relationship between Activity Noise, Voice Parameters, and Voice Symptoms among Female Teachers

“…The same proportion of teachers talked with raised voice levels, ≥86 dB (at 0.1 m), and no teacher used a relaxed level ≤74 dB (at 0.1 m). There have so far been no reliable reference values, especially for voice SPL recorded by means of a portable voice accumulator, although some data [22, 23] have been published. This study confirms the correlation between noise levels and voice loudness (voice SPL) as shown in both the laboratory environment [12] and field investigations [22].…”

“…There have so far been no reliable reference values, especially for voice SPL recorded by means of a portable voice accumulator, although some data [22, 23] have been published. This study confirms the correlation between noise levels and voice loudness (voice SPL) as shown in both the laboratory environment [12] and field investigations [22]. Our results also showed that the change in voice loudness followed the change in the activity noise levels and that the majority of the teachers increased the loudness of their voices up to 9 dB apace with the increasing noise level.…”

“…To the best of our knowledge, only 2 research groups, Echternach et al [22] and Södersten et al [23], used an accelerometer (VoxLog) similar to ours for activity noise level measurement during teaching. Both studies report 9 dB higher values for activity noise level than the present study.…”

“…Furthermore, variations in time window settings may have also influenced the differences. We used a 1-min time window, as did Södersten et al [23], whereas Echternach et al [22] used a 5-s time window. Possible variation in statistical methods could explain some of the differences: we used medians, while Södersten et al and Echternach et al used means.…”