Room Mode / Standing Wave Calculator

www.MarkTAW.com/recording/Acoustics/RoomModeStandingWaveCalcu.html (printable version)

Room Mode / Standing Wave Calculator
A Room Mode / Standing Wave calculator to help you avoid some number crunching.

This tool is provided as an easy way to calculate Room Modes or Standing Waves in an enclosed rectangular space. You need to look out for Modes that are close together and below about 300hz.

Enter the dimension of your space and the speed of sound (distance per second) and click "Submit". Use either feet or meters for everything. You can't mix feet and meters or the calculations will be all wrong. Use feet and a decimal remainder (no inches).

Sound at sea level = 1130 feet per second, or 344 meters per second.

I make no gaurantees about this information, use it at your own discretion. These mathematical models will not replace accurate measurements by a competent professional.

Speed of Sound		Meters/Second or Feet/Second
Length of Room		Meters or Feet (in Decimal form)
Width of Room		Meters or Feet (in Decimal form)
Height of Room		Meters or Feet (in Decimal form)
Calculate Room Modes

Axial Modes - Involve Two Parallel Surfaces - opposite walls, or the floor and ceiling. These are the strongest modes.

Length		Width		Height
Mode	Frequency	Mode	Frequency	Mode	Frequency
1 0 0		0 1 0		0 0 1
2 0 0		0 2 0		0 0 2
3 0 0		0 3 0		0 0 3
4 0 0		0 4 0		0 0 4
5 0 0		0 5 0		0 0 5
6 0 0		0 6 0		0 0 6
7 0 0		0 7 0		0 0 7
8 0 0		0 8 0		0 0 8
9 0 0		0 9 0		0 0 9

Tangential Modes - Involve Two sets of Parallel Surfaces - all four walls, or two walls the ceiling and the floor. These are about half as strong as the Axial modes.

Length & Width		Length & Height		Width & Height
Mode	Frequency	Mode	Frequency	Mode	Frequency
1 1 0		1 0 1		0 1 1
1 2 0		1 0 2		0 1 2
1 3 0		1 0 3		0 1 3
1 4 0		1 0 4		0 1 4
2 1 0		2 0 1		0 2 1
2 2 0		2 0 2		0 2 2
2 3 0		2 0 3		0 2 3
2 4 0		2 0 4		0 2 4
3 1 0		3 0 1		0 3 1
3 2 0		3 0 2		0 3 2
3 3 0		3 0 3		0 3 3
3 4 0		3 0 4		0 3 4
4 1 0		4 0 1		0 4 1
4 2 0		4 0 2		0 4 2
4 3 0		4 0 3		0 4 3
4 4 0		4 0 4		0 4 4

Oblique Modes - Involve all six surfaces - four walls, the ceiling and the floor. These are about one quarter as strong as the Axial modes, and half as strong as the tangential modes.

Mode	Frequency	Mode	Frequency	Mode	Frequency	Mode	Frequency
1 1 1		1 1 2		1 2 1		2 1 1
2 2 2		2 2 1		2 1 2		1 2 2

Ethan Winer has a great DOS utility that shows you graphically the first modes of your room so you don't have to figure out yourself where the pileups are.