Room sound homogeneous decay holds for typical rooms but can be engineered away

Evidence

The decay of sound energy in the room is no longer a single exponential decay with a time constant proportional to the average absorption in the room. Instead, there are several decay times. The shortest one tends to be due to the diffuse sound field, whereas the longer ones tend to be due to the resonant modes in the room. This results in excess energy at those frequencies with the attendant degradation of the sound in the room. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1996 (#qualifies, via linked claim)

Equation 6.16 gives us the time between surface interactions, and at each of these interactions, α is the proportion of the energy absorbed, where α is the average absorption coefficient discussed earlier. If α of the energy absorbed at the surface, then (1 − α) is the proportion of the energy reflected back to interact with further surfaces. At each surface a further proportion, α, of energy will be removed, so the proportion of the original sound energy that is reflected will reduce exponentially. The combination of the time between reflections and the exponential decay of the sound energy, through progressive interactions with the surfaces of the room, can be used to derive an expression for the length of time that it would take for the initial energy to decay by a given ratio. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1830 (#exemplifies, via linked claim)

Categorization

• XREF: connects to: Modal decay analysis governs room acoustics below the critical frequency — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2038; Room sound energy decays exponentially through repeated surface absorptions — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1830; Sabine experimentally verified exponential sound decay in a reverberant room (+9 more)

Broader Connections

• Room modes produce multiple decay times instead of a single exponential reverberation #qualifies (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1996
• Room sound energy decays exponentially through repeated surface absorptions #exemplifies (0.82) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1830
• Sabine experimentally verified exponential sound decay in a reverberant room #exemplifies (0.80)
• Non-environment rooms suppress all but direct sound for clearer audio detail and imaging #exemplifies (0.80)
• The diffuse field assumption underpins room acoustics predictions but fails at low frequencies #qualifies (0.80)
• Modal decay analysis governs room acoustics below the critical frequency #qualifies (0.78) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2038
• No reverberation-time formula has universal applicability across rooms #corroborates (0.78)
• Physical sound absorption can be strong enough to measurably alter room reverberation #expands (0.75)
• Diffuse surfaces make room acoustics degrade gradually away from the sweet spot #expands (0.72)
• Distributing absorption in small random amounts around a room improves sound diffusion #expands (0.72)