Every room has a low-frequency limit below which reverberation time is meaningless
Evidence
Because all rooms have modes in their lower frequency ranges, there will always be a frequency below which the modal effects dominate and the room can no longer be treated as diffuse. … An important consequence of this is that the room no longer supports a diffuse field in the modal region and so the reverberation time concept is invalid in this frequency region. Instead an approach based on modal decay should be used. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2066
Categorization
Category: Factual Claims
- DEFINE: Defines the modal versus diffuse field transition and why reverberation time fails below it.
Related
- Every room has a frequency below which modal effects break the diffuse-field assumption (similarity 0.91)
- No reverberation-time formula has universal applicability across rooms (similarity 0.89)
- Recommendable reverberation times range from 2 seconds down to 0.35 seconds by room type (similarity 0.87)
- Modal decay analysis governs room acoustics below the critical frequency (similarity 0.86)
- Below 213 Hz a living room must be analyzed by modal decay, not reverberation (similarity 0.86)
- Reverberation times range from fractions of a second to ten seconds (similarity 0.85)
- Low absorber rooms raise overall sound level because reverberant energy persists longer (similarity 0.85)
- Room modes produce multiple decay times instead of a single exponential reverberation (similarity 0.85)
- Concert hall reverberation times range from one to two seconds (similarity 0.85)
- Sabine’s reverberation formula founded architectural acoustics but fails for high absorption (similarity 0.85)
- A typical living room’s reverberation time rises at low frequencies, producing a boomy sound (similarity 0.84)
- Reverberant fields typically color perceived sound with excess bass that equalization must fix (similarity 0.84)
- Very dead rooms lack a true reverberant field entirely (similarity 0.84)
- Reverberation time depends on room volume and surface area, not absorption alone. (similarity 0.84)
- A single slope measurement of dB decay directly yields the reverberation time (similarity 0.84)
Broader Connections
- Every room has a low-frequency limit below which modal effects dominate
#expands(0.95) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2018 - Even anechoic rooms have a low-frequency operational limit
#expands(0.90) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2066 - No reverberation-time formula has universal applicability across rooms
#corroborates(0.80) — Toole, Floyd E, Sound reproduction- the acoustics and…, 1249 - Reverberation calculations often lack absorption data below 125 Hz
#qualifies(0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1880 - A typical living room’s reverberation time rises at low frequencies, producing a boomy sound
#exemplifies(0.75) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1896