Since the wavelengths at these frequencies fit exactly into the room, you'll find
much higher sound levels at the room boundaries (and particularly in the corners,
where two or more sets of modes coincide), plus a series of low and high levels
(minima and maxima) spaced between the boundaries.
If you're lucky, or have built the room with acoustics in mind, the three sets of
Axial modes will be smoothly spaced from the lowest roommode frequency to several
hundred Hertz, beyond which their numerous peaks and troughs can be effectively
treated using acoustic tiles. If not, some frequencies from the different mode
series will coincide, causing even larger peaks and troughs in your frequency
response.
The very worst case is a cubic room, since all three mode series will be identical,
but thankfully there are published lists of preferred ratios for room dimensions
that ensure relatively smoothly spaced modes.
