Improved Rotating Diffuser for Reverberation Chambers

Abstract

An experiment was conducted with a rotating diffuser consisting of several acoustically reflective panels in the form of a truncated cone to determine if it would give more efficient diffusion of a reverberant room's modal patterns than a typical flat-panel rotating vane. The diffuser construction was such that deviations from the purely conical shape could be made to determine the effect of changes in shape on the degree of diffusion. Since the amount of diffusion in most low-frequency regions varies with the location of the rotating vane within the room, it was also considered to be possible that a spatial traverse of the vane would result in a space-averaged diffusion and more uniform over-all modal response. To determine the effect of such a spatial traverse, the drive mechanism of the conical diffuser was modified so that the vane's axis of rotation simultaneously traversed an asynchronous orbit. It was found that the orbital-rotating conical diffuser gave a significant flattening of the room's low-frequency modal response and was much superior to the rotating flat diffuser.