Standing-wave modes produce several decay times, leaving excess energy at modal frequencies

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 (#corroborates, via linked claim)

Categorization

• XREF: connects to: Opposing waves cancel only momentarily because energy persists in kinetic form; Standing waves arise when wall spacing equals half-wavelength multiples; Long-sustaining vibrations favor narrow frequency ranges (+5 more)

Related

• Room modes produce multiple decay times instead of a single exponential reverberation (similarity 0.90)
• A room mode’s length relative to mean free path sets its decay time (similarity 0.90)
• Modal absorption is frequency dependent, stretching decay time at standing-wave frequencies (similarity 0.90)
• Every room has a frequency below which modal effects break the diffuse-field assumption (similarity 0.84)
• Room standing waves cause sound pressure to vary with listening position (similarity 0.84)
• Opposing waves cancel only momentarily because energy persists in kinetic form (similarity 0.84)
• Room sound homogeneous decay holds for typical rooms but can be engineered away (similarity 0.84)
• Modal decay analysis governs room acoustics below the critical frequency (similarity 0.83)
• Modal decay differs from diffuse decay because reflection paths are fixed, not random. (similarity 0.83)
• Standing waves create loudness dips at room midpoints (similarity 0.82)
• A slowly-decaying frequency makes a room ring at that pitch (similarity 0.82)
• A single slope measurement of dB decay directly yields the reverberation time (similarity 0.82)
• Standing waves form when wavelengths match room dimensions (similarity 0.82)
• Room acoustical behavior changes across a broad transition region, not at one frequency (similarity 0.82)
• Room materials’ absorption coefficient varies with frequency (similarity 0.82)

Broader Connections

• Room modes produce multiple decay times instead of a single exponential reverberation #corroborates (0.95) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1996
• Modal decay time depends on mode length relative to the diffuse-field mean free path #expands (0.85)