Modal behavior makes diffuse-field analysis fail in a mid frequency range

Evidence

The modal region: The next region is the modal region in which the modal behavior of the room dominates its acoustic performance. In this region the analysis based on the assumption of a diffuse field is doomed to fail. — David Howard, Jamie Angus, coustics and Psychoacoustics, 2073

Categorization

• DEFINE: Precisely delineates the modal region as one of the three frequency ranges governing room response.
• XREF: connects to: Every room has a frequency below which modal effects break the diffuse-field assumption — David Howard, Jamie Angus, coustics and Psychoacoustics, 2066; Modal bandwidths break diffuse-field assumptions when sound paths exceed the mean free path — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2012; Diffuse-field assumptions hold at high frequencies but break down at low ones — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1774 (+9 more)

Broader Connections

• The diffuse field assumption underpins room acoustics predictions but fails at low frequencies #corroborates (0.92)
• Diffuse-field assumptions hold at high frequencies but break down at low ones #corroborates (0.90) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1774
• Diffuse field assumptions fail when sound paths exceed mean free path #corroborates (0.88)
• Every room has a frequency below which modal effects break the diffuse-field assumption #expands (0.85) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2066
• A defined frequency marks the transition between modal and diffuse acoustic behavior #expands (0.85) — David Howard, Jamie Angus, coustics and Psychoacoustics, 2078
• Modal behavior intensifies as wavelength approaches the room’s mean free path #expands (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2029
• Modal bandwidths break diffuse-field assumptions when sound paths exceed the mean free path #expands (0.82) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2012
• Modal decay analysis governs room acoustics below the critical frequency #expands (0.82) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2038
• A single critical frequency marks the modal to diffuse transition #expands (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2025
• A transition frequency separates modal from ray acoustical behavior in rooms #expands (0.80) — Toole, Floyd E, Sound reproduction- the acoustics and…, 475
• Pure diffuse-field calibration yields inadequate bass and low preference ratings #exemplifies (0.78)
• Low absorption sustains strong modal variation in rooms at higher frequencies than predicted #complicates (0.75) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2033