Real listening rooms produce semi-reflective fields, not free or diffuse fields

Evidence

What is not well known is that the serious deliberations leading to these recommendations had to do with reverberation chambers for the purpose of measuring the sound power output of noisy mechanical devices. … Nevertheless, these concepts migrated into the audio field, and certain room dimensional ratios have been promoted as having especially desirable characteristics for listening. In normal rooms, the benefits apply only to low frequencies. Bolt (1946) makes this clear in the rarely seen “range of validity” graph that accompanies his “blob,” Figure 8.5. This shows that, in an 85 m3 (3,000 ft3) room, the optimum ratios are effective from about 40 to 120 Hz. — , Toole, Floyd E - Sound reproduction-…, 900 (#corroborates, via linked claim)

Categorization

• XREF: connects to: Dipole surround speakers degraded direct sound without creating effective diffuse fields.; Home listening rooms should avoid diffuse fields because engineers control spatial cues; True diffuse sound fields cannot form in small absorptive listening rooms (+15 more)

Related

• True diffuse sound fields cannot form in small absorptive listening rooms (similarity 0.91)
• Small listening rooms lack diffuse reverberation and contain only early reflections (similarity 0.90)
• In small rooms reflections arrive early and never form a diffuse field (similarity 0.89)
• Dipole surround speakers degraded direct sound without creating effective diffuse fields. (similarity 0.89)
• Statistical acoustics and classical critical distance do not apply in small rooms (similarity 0.88)
• Diffuse-field regions sound best because modes are minimal and level is even (similarity 0.88)
• Smaller listening areas require less acoustic absorption treatment (similarity 0.88)
• Room boundary reflections are the second loudest sounds a listener hears (similarity 0.88)
• Diffuse-field equations fail in geometrically extreme rooms (similarity 0.87)
• Reverberant fields supply most perceived loudness in normal rooms (similarity 0.86)
• A small listening room’s first reflections mask the recorded acoustic space (similarity 0.86)
• Domestic hi-fi listening is dominated by reverberant rather than direct sound (similarity 0.86)
• Diffuse surfaces make room acoustics degrade gradually away from the sweet spot (similarity 0.86)
• Early reflections are beneficial for recreational home listening but optional to treat. (similarity 0.86)
• We mostly listen to recorded sound in small rooms, not performance halls (similarity 0.85)

Broader Connections

• The diffuse field assumption underpins room acoustics predictions but fails at low frequencies #corroborates (0.82)
• The ideal room ratio dogma originated from industrial reverberation chambers, not listening rooms #corroborates (0.80) — , Toole, Floyd E - Sound reproduction-…, 900
• Room acoustics requires modeling direct sound then early reflections #expands (0.78)
• Small playback rooms impose their own early reflections on recorded sound #exemplifies (0.78)
• Bolt’s room-ratio studies targeted reverberation chambers, not listening rooms #expands (0.75) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1542
• Statistical acoustics and classical critical distance do not apply in small rooms #corroborates (0.75) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1312
• Non-environment rooms suppress all but direct sound for clearer audio detail and imaging #qualifies (0.72)
• Floor reflections are an inherent part of normal human listening #exemplifies (0.72) — , Toole, Floyd E - Sound reproduction-…, 790
• Resonances near anechoic thresholds become audible again in reflective rooms #qualifies (0.72) — , Toole, Floyd E - Sound reproduction-…, 399
• Smaller listening areas require less acoustic absorption treatment #qualifies (0.72)