Reverberation-Time Measurements in the Philadelphia Academy of Music
James E. West, Gerhard Martin Sessler, James L. Flanagan · The Journal of the Acoustical Society of America · 1973
The reverberation time of the unoccupied Academy of Music in Philadelphia was measured utilizing the method of integrated tone-burst decays [M. R. Schroeder, J. Acoust. Soc. Amer. 37, 409 (1965)]. Third-octave tone bursts covering the frequency range from 50 to 5000 Hz were used as test signals. The measurements were taken at 14 different microphone positions throughout the Hall for two loudspeaker locations on stage. In addition, two different ceiling arrangements of the stage enclosure were implemented; namely, a flared tilt (normally used) and an experimental horizontal configuration. The subjectively important initial reverberation time T1 (extrapolated from the decay over the first 10 dB of the integrated response) as well as the final reverberation time T2 (extrapolated from the decay over the range −10 to −30 dB) were evaluated on a digital computer. The results for the octave centered at 500 Hz, averaged over all positions, are: T1 = 1.2 sec, T2 = 1.4 sec for the flared stage ceiling; and T1 = 1.3 sec, T2 = 1.5 sec for the horizontal ceiling.