Impulse response analysis replaces mode analysis once mode density gets high.

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 (#expands, via linked claim)

Categorization

• XREF: connects to: Frequency, phase, and impulse responses are interchangeable transforms of each other; Modal decay analysis governs room acoustics below the critical frequency — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2038

Broader Connections

• Modal decay analysis governs room acoustics below the critical frequency #expands (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2038
• Frequency, phase, and impulse responses are interchangeable transforms of each other #qualifies (0.80)