When is diffuse-field theory accurate?

M. Hodgson


Diffuse-field theory is used by practitioners to predict sound fields in rooms of every type. Often forgotten is the fact that the theory is based on assumptions which may limit its applicability. If the theoretical assumptions do not hold in the case of a particular room for which predictions are to be done, the predictions may not be accurate. The objective of this paper is to review what is known about the applicability of diffuse-field theory. This is mainly based on extensive work by Kuttruff (1976) and by the authors comparing predictions by diffuse-field theory and a ray-tracing model. It considers two versions of diffuse-field theory-the Eyring and Sabine versions-and the prediction of both sound decay/reverberation time, and steady-state sound pressure level. Note that both diffuse-field theory an ray-tracing are energy-based models which ignore wave effects and thus may be inherently inaccurate at lower frequencies


architectural acoustics; reverberation; diffuse-field theory; sound fields; rooms; ray-tracing model; sound decay; reverberation time; steady-state sound pressure level

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