Avoiding commensurate room dimensions prevents overlapping modal frequencies that cause acoustic problems

Evidence

The equation also shows that if any of the dimensions are integer multiples of each other, then some of the modal frequencies will be the same, which can cause problems. It is therefore better to choose noncommensurate ratios for the wall dimensions to ensure that the modes are spread out as much as possible. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1978

Categorization

• DEFINE: Defines why noncommensurate room ratios matter — integer-multiple dimensions cause coincident standing-wave frequencies.
• QUESTION: What specific problems do coinciding modal frequencies cause — coloration, uneven bass response, reverberation peaks?
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1978
• XREF: connects to: 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; Changing room geometry barely alters loudspeaker quality rankings (+8 more)

Related

• Room modes are determined by the linear dimensions of opposing surfaces (similarity 0.91)
• Spatially static resonant modes cause sound level to vary across a room (similarity 0.90)
• Changing room geometry barely alters loudspeaker quality rankings (similarity 0.89)
• Spatially proportional room dimensions create coincident resonant modes (similarity 0.88)
• Dimensionally symmetrical rooms are acoustically asymmetrical due to construction details (similarity 0.87)
• Axial mode frequencies are computable from room dimensions by a simple formula (similarity 0.85)
• Dimensional room symmetry does not guarantee acoustic symmetry (similarity 0.84)
• Hard-walled rooms behave as three-dimensional resonators with many audible modal frequencies (similarity 0.84)
• Reshaping a room’s walls only obscures resonances rather than removing them (similarity 0.84)
• Room mode density rising smoothly with frequency signals good acoustics (similarity 0.83)
• Rectangular rooms are preferred because their modes are predictable (similarity 0.83)
• Angling room walls changes resonance frequencies but cannot eliminate them (similarity 0.82)
• Changing room shape relocates resonances but never removes them (similarity 0.81)
• Exciting multiple room modes instead of one reduces frequency and spatial sound variation (similarity 0.81)
• Non-parallel walls do not eliminate room modes (similarity 0.81)

Broader Connections

• Spatially proportional room dimensions create coincident resonant modes #corroborates (0.90)