Room acoustics
Schroeder frequency
The transition frequency below which a room behaves as a set of discrete resonances and above which reflections blend into a diffuse field.
Below the Schroeder frequency, room modes are sparse enough to be heard individually as peaks and nulls. Above it, modes are so densely packed that the response smooths into statistical reverberation. Small, live rooms have a high transition; large, damped rooms a low one.
It sets the treatment strategy. Problems below the transition need bass traps, subwoofer placement, and EQ, since thin panels do nothing there. Problems above it are handled by absorption and diffusion at reflection points.
The formula is f = 2000 x sqrt(RT60 / V), with RT60 in seconds and V in cubic meters. A 60 cubic meter room with an RT60 of 0.4 s transitions near 160 Hz; most home theaters land between 100 and 250 Hz.
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