Diffusion replaces sparse loud early reflections with a dense set of quiet ones

Evidence

So diffusion can result in a reduction of the amplitude of the early reflection from a given point. However, there will also be more reflections due to the diffusion arriving at the listening position from other points on the wall, as shown in Figure 7.30. Surely this negates any advantage of the technique? A closer inspection of Figure 7.30 reveals that although there are many reflection paths to the listening point, they are all of different lengths and hence time delays. The extra paths are also all of a greater length than the specular path, shown dashed in Figure 7.30. Furthermore, the phase-reflection diffusion structure will add an additional temporal spread to the reflections. As a consequence, the initial time-delay gap will be filled with a dense set of lowlevel early reflections instead of a sparse set of higherlevel ones, as shown in Figure 7.31. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2322

Categorization

• DEFINE: Explains the mechanism of diffusion in acoustics: redistributing reflection energy in time and amplitude rather than absorbing it.
• XREF: Connects to the book’s earlier treatments of early reflections, time-delay gaps and stereo imaging, one of the core psychoacoustic mechanisms of room perception. — connects to: Diffusing early reflections lowers their level without absorbing the sound energy — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2315