Critical listening research on reproduced sound in diffuse environments.

Abstract

In critical listening rooms designed to monitor precisely small signal processing changes, what can be heard is influenced by the room’s modal response and the degree to which reflections are controlled by absorptive, reflective, and diffusive boundary surfaces. In exploring the problem of room acoustics affecting the results of such important listening activities, it is informative to explore the boundary conditions. For example, the acoustics industry utilizes absorption and reverberation chambers to explore related auditory phenomena. Recently, a diffusion chamber was created with broadband diffusion on walls and ceiling. Modal frequencies were also controlled with dedicated plate resonators effective down to 50 Hz. Impulse response measurements in this diffuse chamber revealed a dense reflection pattern 30 dB or more below the direct sound. The initial perception in this room was precise sonic images, a comfortable sense of ambiance and an apparent transparency to the subtleties of reproduced imagery that support decisions of sound engineers. Related experiments being carried out in other controlled listening rooms will be reviewed to place the current work in context.