Room resonances above 200 Hz overlap heavily, forcing isolated modes below that threshold

Evidence

As frequency f increases and the spacing between adjacent resonances decreases, the resonances will begin to overlap. Below this frequency, resonant modes tend to be isolated; above, they tend to be overlapping. The modes may be relatively high Q, but they are too numerous to exist in splendid isolation. The transition between the two regimes is called the Schroeder frequency, after Manfred Schroeder (1926–2009), who introduced it in the context of concert halls. For frequencies above 200 Hz or so in a typical large room, there are so many different possible resonances, each corresponding to a different mode, that typically a few to many decaying modes (resonances) share any given frequency. — Eric J. Heller, Why You Hear What You Hear- An…, 1150

Categorization

• DEFINE: Defines the Schroeder frequency: the transition point in a room where resonances change from isolated to overlapping, around 200 Hz in typical large rooms.