Effects of added absorption on the vocal exertions of talkers in a reverberant room.

Occupational speech users such as schoolteachers develop voice disorders at higher rates than the general population. Previous research has suggested that room acoustics may influence these trends. The research reported in this paper utilized varying acoustical conditions in a reverberant room to assess the effects on vocal parameters of healthy talkers. Thirty-two participants were recorded while completing a battery of speech tasks under eight room conditions. Vocal parameters were derived from the recordings and the statistically significant effects of room acoustics were verified using mixed-model analysis of variance tests. Changes in reverberation time (T20), early decay time (EDT), clarity index (C50), speech transmission index (STI), and room gain (GRG) all showed highly correlated effects on certain vocal parameters, including speaking level standard deviation, speaking rate, and the acoustic vocal quality index. As T20, EDT, and GRG increased, and as C50 and STI decreased, vocal parameters showed tendencies toward dysphonic phonation. Empirically derived equations are proposed that describe the relationships between select room-acoustic parameters and vocal parameters. This study provides an increased understanding of the impact of room acoustics on voice production, which could assist acousticians in improving room designs to help mitigate unhealthy vocal exertion and, by extension, voice problems.