This definitive guide covers the design and application of absorbers and diffusers in acoustics. Surface diffusion is a relatively young subject area, and diffuser design, application and characterisation are often not well understood. Although there is greater knowledge of absorption, it is also informed by new research. As two of the main design tools for altering the acoustic conditions of rooms, the correct use of absorbers and diffusers is important to the creation of quality acoustics. This text details the evolution and the current state of the art in diffuser and absorber research...