Reverberant sound is assumed to strike all surfaces with equal probability in modeling.

Evidence

Therefore one must take note of an important assumption behind Equation 6.6, which is that the reverberant sound visits all surfaces with equal probability and from all possible directions. This is known as the “diffuse field assumption.” It can also be looked at as a definition of a diffuse field. In general, the assumption of a diffuse field is reasonable, and it is usually a design goal for most acoustics. However, it is important to recognize that there are situations in which it breaks down, for example at low frequencies. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1774

Categorization

• DEFINE: Defines the diffuse field assumption that underpins reverberation calculations.
• QUESTION: Why does the diffuse field assumption break down at low frequencies — what physical mechanism causes the failure?

Related

• Reverberation equations fail in extreme geometries where surfaces are visited unequally (similarity 0.86)
• Diffuse reverberant fields let power in the field be equated to sound pressure level (similarity 0.86)
• Reverberation time formulas rest on statistical assumptions about sound fields (similarity 0.85)
• A reverberant field requires roughly twenty or more reflections to exist. (similarity 0.81)
• The reverberant field is an integrated sum of intensities arriving from all directions (similarity 0.81)
• In steady state, reverberant sound level is uniform throughout a room. (similarity 0.81)
• Beyond the reverberation distance, loudness stays constant while reverberance increases. (similarity 0.81)
• Sound from a source falls 6 dB per distance doubling until reverberation takes over (similarity 0.80)
• Reverberant sound level stays constant with listener position because reflections arrive from all directions (similarity 0.80)
• Perfect diffusion is an unattainable ideal in real rooms (similarity 0.80)
• Very dead rooms lack a true reverberant field entirely (similarity 0.80)
• Diffuse-field equations fail in geometrically extreme rooms (similarity 0.80)
• Absorption at each reflection governs how fast reverberation decays (similarity 0.79)
• A large low-absorption area can outweigh a small high-absorption one in a room (similarity 0.79)
• Reverberant sound level is position-independent while direct sound varies with position (similarity 0.79)