Diffusion is the scattering and weakening of reflected sound. A properly diffused reflection produces a more natural sound, contributing to enhanced Ambience in a room.

If an incident sound wave possesses 90 dB of sound energy, a properly diffused reflection will typically possess 85-87 dB of sound energy. Additionally, the angle of reflection is no longer related to the angle of incidence, as the sound is scattered among a wider angle. By its very nature, Diffusion obscures the source location of a sound.

The frequencies affected by a diffuser are related to its size, geometry, material, design, and placement.

Typical diffusion devices include polycylindrical diffusers, quadratic residue diffusers, and reflection phase grating diffusers.