Diffuse-field equations fail in geometrically extreme rooms

Evidence

However, one must be careful in taking this result to extremes. A long and very thin cylinder will have a large surface area, but Equation 6.6 will not predict the reverberation level correctly because in this case, the sound will not visit all the surfaces with equal probability. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1772

Categorization

Category: Causal Relationships

• QUESTION: When does a room’s geometry push it outside the diffuse-field assumptions, and do real venues like corridors or tunnels cross that line?

Related

• The Sabine formula assumes diffuse sound that real rectangular rooms rarely produce (similarity 0.87)
• Wavefield synthesis fails unless the room is completely anechoic (similarity 0.86)
• Geometric acoustics fails on diffraction at low frequencies in complex rooms (similarity 0.86)
• Real listening rooms produce semi-reflective fields, not free or diffuse fields (similarity 0.86)
• Rectangular rooms fail to randomize sound directions, violating Sabine theory (similarity 0.85)
• True diffuse sound fields cannot form in small absorptive listening rooms (similarity 0.85)
• Diffuse-field regions sound best because modes are minimal and level is even (similarity 0.85)
• In small rooms reflections arrive early and never form a diffuse field (similarity 0.84)
• Diffuse surfaces make room acoustics degrade gradually away from the sweet spot (similarity 0.84)
• The diffuse field assumption underpins room acoustics predictions but fails at low frequencies (similarity 0.84)
• Flat rectangular rooms do not diffuse sound; slight wall curvature does (similarity 0.83)
• Statistical acoustics and classical critical distance do not apply in small rooms (similarity 0.83)
• Room absorption determines the steady-state level of reverberant sound (similarity 0.82)
• Dipole surrounds only worked for one row of listening positions (similarity 0.82)
• Standing waves from room boundaries prevent diffuse sound fields at low frequencies. (similarity 0.82)

Broader Connections

• The diffuse field assumption underpins room acoustics predictions but fails at low frequencies #expands (0.95) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1774
• Rectangular rooms fail to randomize sound directions, violating Sabine theory #expands (0.90) — Eric J. Heller, Why You Hear What You Hear- An…, 2511
• True diffuse sound fields cannot form in small absorptive listening rooms #corroborates (0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1256
• Real listening rooms produce semi-reflective fields, not free or diffuse fields #corroborates (0.85) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1769