Speakers’ comfort and voice level variation in classrooms: Laboratory research

Abstract

Teachers adjust their voice levels under different classroom acoustics conditions, even in the absence of background noise. Laboratory experiments have been conducted in order to understand further this relationship and to determine optimum room acoustic conditions for speaking. Under simulated acoustic environments, talkers do modify their voice levels linearly with the measure voice support, and the slope of this relationship is referred to as room effect. The magnitude of the room effect depends highly on the instruction used and on the individuals. Group-wise, the average room effect ranges from -0.93 dB/dB, with free speech, to -0.1 dB/dB with other less demanding communication tasks as reading and talking at short distances. The room effect for some individuals can be as strong as -1.7 dB/dB. A questionnaire investigation showed that the acoustic comfort for talking in classrooms, in the absence of background noise, is correlated to the decay times derived from an impulse response measured from the mouth to the ears of a talker, and that there is a maximum of preference for decay times between 0.4 and 0.5 s. Teachers with self-reported voice problems prefer higher decay times to speak in than their healthy colleagues.

Speaker-Oriented Classroom Acoustics Design Guidelines in the Context of Current Regulations in European Countries

“…Room acoustics parameters relevant for a speaker, their relationship with voice, and their prediction models have been presented separately in previous research [1,13,18].…”

“…Two concepts related to the voice of the teacher are dened in this context: vocal comfort and vocal eort. The vocal comfort in a room is a subjective attribute that is directly correlated to the positive evaluation of the room for speech purposes and to the perceived support, and negatively correlated to the feeling of having to raise the voice and to the tiredness after speaking longly in the room [1]. The vocal eort, according to Traunmüller and Eriksson [2], is a physiological magnitude dierent from vocal intensity, which accounts for the changes in voice production required for the communication at dierent distances, under dierent noise or room acoustics conditions.…”

Effects of voice style, noise level, and acoustic feedback on objective and subjective voice evaluations

“…4 It appears to decrease with the speaker's perceived fatigue and the sensation of needing to increase the voice level. 5 Vocal comfort can be defined as the capacity to self-regulate vocal behaviour, e.g., sound pressure level (SPL) or intensity. The sensation of control relates to the capacity to adjust the voice to maintain a level that is suitable for communication given the environmental conditions.…”

Assessment of vocal intensity in lecturers depending on acoustic properties of lecture rooms

“…1 i 4). Wyniki potwierdzają efekt Lombarda polegający na wzroście natężenia głosu mówiącego przy wzroście hałasu tła akustycznego [4,5,11,[14][15][16]18,[22][23][24]. Poziom natężenia głosu lektorów przedstawiony na rycinie 1. świadczy zarówno o dużym zróżnicowaniu poziomu natężenia głosu lektorów (58-70 dB), jak i dużej różnicy wyników próbek każdego z lektorów (największa różnica poziomu natężenia głosu lektora to 16 dB).…”