Posted by Ethan Winer (M) on November 20, 2004 at 06:23:57

In Reply to: Big(ish) Rooms posted by Rob G. on November 19, 2004 at 07:07:37:

Rob,

I think you're missing a few points. First, each room dimension has multiple resonances at related frequencies. So a 32 foot length that resonates at 17.6 Hz also resonates at 35, 53, 71, 88, etc Hz. As you go higher the resonances contribute less, but they're still active.

Second, room resonances are only part of the room's contribution to low frequency response. Just as important is basic acoustic interference, which causes peaks and deep nulls at 1/4 wavelength and related multiples away from the walls, floor, and ceiling. So regardless of what a mode calculator reports, you'll still have peaks and deep nulls at all low frequencies, depending on where you are in the room.

Third, low frequency response is only one part of the room's contribution. The other is modal ringing, which is sort of like low frequency reverb, and occurs at all the resonant frequencies of each "harmonic series" for each dimension. Modal ringing is a huge contributor to muddy bass since it causes some notes to ring for longer than others. When a bass note sustains after the bass player has stopped playing, it conflicts with other subsequent notes and makes it difficult to discern which notes they are. You can hear that something is going on down there, but you can't quite make out what.

--Ethan