The comparative distribution of sound pressure variations throughout a given space, or the process by which a sound wave is distributed in the space. If sound pressure is uniformly distributed throughout the space, the sound is said to be well diffused.
Diffusion of sound is important in concert halls, classrooms, studios and the like in order to avoid dead spots, places where the sound is weak or cannot be heard clearly. (Source: Barry Truax - Handbook for Acoustic Ecology CD-ROM Edition. Cambridge Street Publishing, 1999 - CSR-CDR 9901)