Vocal effort and the effect of room acoustics in noisy environments

Vocal effort is a physiological entity that accounts for variation in voice production as loading increases. A subjective evaluation of effort has been associated with Sound Pressure Level (SPL). Several studies have investigated vocal effort, but few have considered the effect of room acoustics on effort. In this experiment, 20 subjects performed vocal tasks in the presence of babble noise in anechoic, semi-reverberant and reverberant environments. The room acoustics in each environment were modified by introducing two reflective panels placed at 45 from the axis mouth at 0.5 m from the subject. Tasks were performed at normal and loud volumes. After each task, the subject answered questions addressing their perception of vocal effort, comfort, control, and the clarity of their own voice. Variation in SPL for each subject was measured per task. SPL decreased when the panels were present. An assessment of self-reported effort, control, comfort and clarity is also presented. The effect of the reverberation on vocal effort is discussed. The results indicate that while keeping reverberation time constant, reflective surfaces may be used to reduce vocal effort.