A case study on the new reverberation room built in University of Technology Sydney

摘要

A new reverberation room has just been built at Centre for Audio, Acoustics and Vibration in University of Technology Sydney. This paper reports some key parameters of the room, which include the background noise and its spectrum, the number of modes in low frequency bands, the cut-off frequency, the standard deviation of the spatial variations of the reverberant field, the decay curves of the sound pressure level versus time, the reverberation times, and the absorption coefficients. The volume of the room is approximately 232 m~3 with a total surface area of approximately 247 m~2. The averaged overall background noise level inside the room is 23.1 dB and 18.1 dBA, the number of modes is greater than 30 in one-third-octave bands with centre frequencies of 160 Hz and above, the standard deviation of the sound pressure levels is less than 1.5 dB in one-third-octave bands with centre frequencies of 125 Hz and above, and the decay curves of sound-pressure level versus time is linear in all one-third-octave bands. The reverberation time of the room can be as long as 20 s in the low frequency range around 100 Hz, and the shortest reverberation time is about 3.1 s in the high frequency range around 5000 Hz. The equivalent sound absorption areas of the empty room in all one-third-octave bands are smaller than the threshold values specified in the standard, and the curve is smooth without any dips or peaks which differ by more than 15% from the mean values of two adjacent one-third-octave bands. The sound absorption coefficients in all frequency bands of the empty reverberation room are less than 0.02.