Does reverberation perception differ in virtual spaces with unrealistic sound reflections?

Reverberation caused by sound reffected off surfaces and objects is present in abundance in everyday life. Yet, in most situations we are unaware of it. This is due to the ability of our auditory system to adapt to the incoming sound reffections, which results in increased echo thresholds, i.e. the minimum delay to hear a reffection as an echo is increased after the echo was heard repeatedly. Changes in the directional pattern of sound reffections disturb the adaptation process and for a short time after the change, reffections become audible. Besides a few notable exceptions, this process has been studied mainly with single reffections rather than with realistic reverberation. The present study addresses the question how changes in the reffection pattern of a reverberant environment are perceived. For the study, realistic simulations of reverberation in a room are created using a high order image source model. By altering parameters of individual image sources, in particular their direction, unrealistic reffection patterns are created which nevertheless maintain key properties of the room such as the direct-to-reverberant ratio and T60. This study tests the hypothesis that, compared to realistic reverberation patterns, differences can be observed in the release from adaptation for unrealistic reverberation patterns. We report the preliminary results from a listening test where the subjects first adapt to reverberant sound signals, and then indicate if a change in the reverberation pattern is perceived or not.