Modal bandwidths break diffuse-field assumptions when sound paths exceed the mean free path

Evidence

Clearly care must be taken when calculating modal bandwidths due to the fact that the diffuse field assumptions no longer apply. In the preceding case, even though an even distribution of absorption was assumed, the decay time and bandwidth were radically different from that predicted by the diffuse field assumptions simply because the path traveled by the sound wave was longer than the mean free path. … Note that, if the absorption remains constant with frequency, the bandwidths of a mode are independent of their frequency—they are simply a function of the modal decay time. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2012

Categorization

• QUESTION: Curious whether there is a workable correction factor for real rooms where absorption clearly varies by surface.
• XREF: connects to: Modal behavior makes diffuse-field analysis fail in a mid frequency range — David Howard, Jamie Angus, coustics and Psychoacoustics, 2073; A defined frequency marks the transition between modal and diffuse acoustic behavior — David Howard, Jamie Angus, coustics and Psychoacoustics, 2078