# How SQUARE is a SQUARE room?

Discussion in 'Archived Threads 2001-2004' started by Phil de Bruin, May 13, 2002.

1. ### Phil de Bruin Auditioning

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Okay - so if a room is perfectly square, or have one dimension exactly twice another - you may encounter resonances that may colour the sound. But just how 'perfectly square' does a room have to be?

Are we talking within a half a foot? An inch? What about if the room in question is pretty god damn square, but the wall protrudes in the middle due to a fireplace? How much difference is that going to make?

/nightdog35/images/filmreel.gif

2. ### John Desmond Stunt Coordinator

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The closer you get to "square" the worse will be your problems. Same thing with multiple dimensions being multiples of each other. So a room that is 8*8*8 will be real bad. Since we're talking about long wavelengths, I would think the 8* 9*8 isn't going to be much better.

3. ### Dustin B Producer

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The room doesn't have to be square or have one dimensione exactly twice the other. Any rectangular room will have 3 axial room modes (plus a bunch of others I don't understand yet). The reason square rooms are said to be the second worst possible shape (cube being the worst) is now two of those 3 axial room modes are the same, resulting in one frequency and it's harmonics being boosted or cut twice.

4. ### Richard Greene Stunt Coordinator

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Example for 18' x 16' x 8' room

showing axial room modes up to 80Hz.):

565/18 = 31Hz (and 31Hz. x 2 = 62Hz.)

565/16 = 35Hz. (and 35Hz. x 2 = 71Hz.)

565/8 = 71Hz.

Assuming room modes are 5Hz. wide there is the potential

for boomy bass at these frequencies:

29 to 33Hz (31Hz. mode)

33 to 37Hz. (35 Hz. mode)

60 to 64Hz. (62Hz. mode)

69 to 73Hz. (71Hz. mode)

69 to 73Hz. (71Hz. mode)

Analysis:

The 31Hz. and 35Hz. modes are adjacent modes that may sound like one broad bass frequency peak from 29 to 37Hz.

The two 71Hz. modes are stacked = potential bass boom

The 62Hz. and 71Hz. modes are close enough so

they may sound like one broad bass frequency peak from

60 to 73Hz.