The amount of wooden material in a closed room and its effect on the reverberation time

Optimal sound-absorbing materials are vital for desirable room acoustics. The effect of wood used for interior wall decoration on the acoustical environment is explored in a controlled room by changing the amount of wall wooden materials. The effect on the interior reverberation time (RT) is reported in this work. The experiment was conducted in a relatively small concrete brick house (approximate dimensions 4.6 × 3.2 × 4.2 m). Results showed that room shape and the arrangement of wooden wall decoration materials were important factors affecting the RT at different receiving positions. As the amount of wall decorating wood materials increased, the interior RT in the house decreased linearly; however, the RT at low frequencies diverged. After the analysis of covariance, all frequency variables were adjusted to the same level and a general regressive formula was developed as RT = C − 0.005 DR. Where RT is the reverberation time (s), DR is the amount of interior wood materials used (%), and the C values were constants that ranged from 0.888 to 1.606 and varied according to the different octave bands. Furthermore, it was found that the increasing influential effect with the DR showed diminishing marginal utility. This means that the influence of DR on RT was not linear, and, therefore, the marginal utility should be considered in order to use wooden panels economically. Part of this report was presented at 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003