Originally Posted by AcidMutant
Coincidentally...
given the dimensions of your room, at 1 bar (normal atmospheric) pressure and 20 degrees C. Given the speed of sound under these conditions is 343.1 meters per second and assuming the room was perfectly rectangular, without objects within it, using:
wavelength = speed of sound / frequency
The prime resonances you could expect in the room (from standing waves) will be at:-
wavelength = c / f, rearranged: c / wavelength = f
343.1 / 4 = 85.775 Hz
343.1 / 3 = 114.367 Hz
343.1 / 2.5 = 137.3 Hz
Also at multiples of these frequencies (harmonics).
Enough of the science tip, guess it's time I went to lie down in a quiet, dark, padded room...