ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aAA12. A preliminary analysis of image shifting in concert halls.

Gilbert A. Soulodre

Dept. of Psych., Carleton Univ., 1125 Colonel By Dr., Ottawa, ON K1S 5B6, Canada

Under typical conditions, the early reflections in a concert hall are attenuated relative to the direct sound and are thus integrated with the direct sound. However, there are instances where, due to focusing effects, the level of a reflection can be greater than or equal to the level of the direct sound. This can result in an apparent shifting of the image away from the true source and toward the source of the reflection. This paper reports on a series of subjective tests designed to provide an initial look at the parameters of the reflected sound which influence image shifting. Tests were conducted using two methods: binaural simulation and multiple loudspeakers in an anechoic chamber. Image shifting was examined as a function of the level, delay, angle of arrival, and spectral content of the reflected sound relative to the direct sound. The results were examined in the context of the Orpheum Theatre in Vancouver where pronounced image shifting occurs at certain locations in the hall due to several large concave surfaces in the ceiling.