Acoustical measurements in rooms with variable acoustics.

A dedicated, computer-based system was developed to perform a complete set of acoustical measurements of recent interest in full-sized rooms and in scale models of rooms. The measurements included reverberation time, early reverberation time, loudness, early-to-late temporal energy ratios, lateral energy fractions, interaural cross correlation, and speech transmission index, among others. Measurements were made at multiple locations in four large multiuse halls with different variable acoustics features. Measurements were made with and without an orchestral shell in place, with a concert wall in use, with a ceiling lowered to close off the upper part of a balcony, with curtains raised and lowered on the walls of a room, and with a curtain used to close off the rear position of a large room. Changes in the various measurements at equivalent seating locations will be presented. The magnitude of the changes are compared to changes perceived by listeners of various acoustical qualities in a recent study [R. P. Cervone etal., J. Acoust. Soc. Am. 89, 1857 (A) (1991)]. [Work supported by NSF.]