Spatially static resonant modes cause sound level to vary across a room

Evidence

Another name for these standing waves in a room is resonant modes, and the frequencies at which they occur are known as “modal frequencies.” Because the modes are spatially static, there will be a strong variation of sound pressure level as one moves around the room, which is undesirable. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1953

Categorization

• DEFINE: Introduces ‘resonant modes’ and ‘modal frequencies’ as the standard terms for room standing waves.
• SEED: Angle: why the ‘sweet spot’ in a listening room is really a standing-wave artifact — a piece on modal frequencies and speaker placement.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1953
• XREF: connects to: Frequency response varies wildly across a hall yet listeners barely notice; Hard-walled rooms behave as three-dimensional resonators with many audible modal frequencies — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 291; Dimensionally symmetrical rooms are acoustically asymmetrical due to construction details — , Toole, Floyd E - Sound reproduction-…, 631 (+11 more)

Broader Connections

• Room boundaries alter a sound source’s radiated power, not just its perceived sound #expands (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2134
• Spatially proportional room dimensions create coincident resonant modes #expands (0.80)
• Avoiding commensurate room dimensions prevents overlapping modal frequencies that cause acoustic problems #expands (0.75)