Modal decay analysis governs room acoustics below the critical frequency

Evidence

As an example, let us calculate the critical frequency of our typical living room. The second equation predicts a slightly lower critical frequency compared with the first one. However, the agreement is surprisingly good. Although the modal overlap has been calculated using a reverberation time and hence a diffuse field assumption, this is probably just valid at this frequency, which represents the boundary between the two regions. The critical frequency results show that, for this room, frequencies below 213 Hz must be analyzed using modal decay time rather than reverberation time. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2038

Categorization

• QUESTION: Worth chasing: does this 213 Hz living-room threshold explain why bass sounds boomy and uneven in small rooms while reverberation descriptions fail there?
• SEED: Article angle: ‘The 213 Hz line’ — why every small-room listening problem, from bookshelf speakers to home studios, lives below the critical frequency.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2038
• XREF: connects to: Impulse response analysis replaces mode analysis once mode density gets high.; Room resonances shift from isolated to overlapping at the Schroeder frequency; Room sound homogeneous decay holds for typical rooms but can be engineered away (+16 more)