Natural variations of vocal effort and comfort in simulated acoustic environments

Many teachers suffer from voice problems related to the use of their voices in the working environment. The noise generated by students and external sound sources (like traffic noise or neighboring classrooms) is a major problem, as it leads to an increased vocal effort. In the absence of high levels of background noise, the room has also an effect on the talker‟s voice. In order to quantify the relative importance of the acoustic environment on the vocal demands for teachers, a laboratory investigation was carried out. Thirteen teachers had to read a text aloud under ten different room acoustic conditions, artificially generated by electroacoustic means. The vocal intensity decreased with the objective parameter support, which quantifies the amount of sound reflections provided by the room at the talker‟s ears,relative to the direct sound, at a rate of -0.21 dB/dB. The reading pace decreased with the reverberation time at a rate of 5 words/minute per s. The sensation of comfort and suitability of the rooms for a talker was investigated using a questionnaire. A non-linear relationship between this magnitude and the reverberation time was observed, defining an optimum range around 0.85 s.