Skip to content
12notez

Room Mode & Standing Wave Calculator

Free · No sign-up · Runs in your browser

Used only for the Schroeder frequency.

Lowest mode
35.2 Hz
Volume
1,632 ft³
Ratio
1.88 : 1.41 : 1
Schroeder frequency
186 Hz
Frequency (Hz).Axial (18)Tangential (79)Oblique (85)Stem height shows the kind of mode, not its level.

Modes per 1/3 octave (Bonello check)

Passes: the count never drops from one band to the next, and no band under 5 modes has coincident modes.

  1. 020 Hz band: 0 modes
  2. 025 Hz band: 0 modes
  3. 031.5 Hz band: 0 modes
  4. 140 Hz band: 1 modes
  5. 150 Hz band: 1 modes
  6. 263 Hz band: 2 modes
  7. 480 Hz band: 4 modes
  8. 6100 Hz band: 6 modes
  9. 9125 Hz band: 9 modes
  10. 23160 Hz band: 23 modes
  11. 37200 Hz band: 37 modes
1/3-octave band center (Hz). Red marks a band that fails on coincident modes.

Axial modes

Axial modes bounce between two facing surfaces and are usually the strongest. Each standing wave has a pressure peak at the wall and a particle velocity peak a quarter wavelength out from it.

AxisOrderFrequencyQuarter wavelength
Length135.2 Hz8.0 ft
Length270.3 Hz4.0 ft
Length3105.5 Hz2.7 ft
Length4140.7 Hz2.0 ft
Width146.9 Hz6.0 ft
Width293.8 Hz3.0 ft
Width3140.7 Hz2.0 ft
Width4187.6 Hz1.5 ft
Height166.2 Hz4.3 ft
Height2132.4 Hz2.1 ft
Height3198.6 Hz1.4 ft
Height4264.8 Hz1.1 ft
All 182 modes up to 300 Hz
FrequencyKindOrder (L, W, H)
35.2 HzAxial1, 0, 0
46.9 HzAxial0, 1, 0
58.6 HzTangential1, 1, 0
66.2 HzAxial0, 0, 1
70.3 HzAxial2, 0, 0
75.0 HzTangential1, 0, 1
81.1 HzTangential0, 1, 1
84.5 HzTangential2, 1, 0
88.4 HzOblique1, 1, 1
93.8 HzAxial0, 2, 0
96.6 HzTangential2, 0, 1
100.2 HzTangential1, 2, 0
105.5 HzAxial3, 0, 0
107.4 HzOblique2, 1, 1
114.8 HzTangential0, 2, 1
115.4 HzTangential3, 1, 0
117.2 HzTangential2, 2, 0
120.1 HzOblique1, 2, 1
124.5 HzTangential3, 0, 1
132.4 HzAxial0, 0, 2
133.1 HzOblique3, 1, 1
134.6 HzOblique2, 2, 1
137.0 HzTangential1, 0, 2
140.4 HzTangential0, 1, 2
140.7 HzAxial0, 3, 0
140.7 HzAxial4, 0, 0
141.2 HzTangential3, 2, 0
144.8 HzOblique1, 1, 2
145.0 HzTangential1, 3, 0
148.3 HzTangential4, 1, 0
149.9 HzTangential2, 0, 2
155.5 HzTangential0, 3, 1
155.5 HzTangential4, 0, 1
155.9 HzOblique3, 2, 1
157.1 HzOblique2, 1, 2
157.3 HzTangential2, 3, 0
159.4 HzOblique1, 3, 1
162.2 HzTangential0, 2, 2
162.4 HzOblique4, 1, 1
166.0 HzOblique1, 2, 2
169.1 HzTangential4, 2, 0
169.3 HzTangential3, 0, 2
170.6 HzOblique2, 3, 1
175.7 HzOblique3, 1, 2
175.8 HzTangential3, 3, 0
175.8 HzAxial5, 0, 0
176.8 HzOblique2, 2, 2
181.6 HzOblique4, 2, 1
182.0 HzTangential5, 1, 0
187.6 HzAxial0, 4, 0
187.9 HzOblique3, 3, 1
187.9 HzTangential5, 0, 1
190.8 HzTangential1, 4, 0
193.2 HzTangential0, 3, 2
193.2 HzTangential4, 0, 2
193.5 HzOblique3, 2, 2
193.6 HzOblique5, 1, 1
196.3 HzOblique1, 3, 2
198.6 HzAxial0, 0, 3
198.8 HzOblique4, 1, 2
198.9 HzTangential0, 4, 1
198.9 HzTangential4, 3, 0
199.3 HzTangential5, 2, 0
200.3 HzTangential2, 4, 0
201.7 HzTangential1, 0, 3
202.0 HzOblique1, 4, 1
204.0 HzTangential0, 1, 3
205.6 HzOblique2, 3, 2
207.1 HzOblique1, 1, 3
209.7 HzOblique4, 3, 1
210.0 HzOblique5, 2, 1
210.7 HzTangential2, 0, 3
211.0 HzOblique2, 4, 1
211.0 HzAxial6, 0, 0
214.7 HzOblique4, 2, 2
215.2 HzTangential3, 4, 0
215.8 HzOblique2, 1, 3
216.1 HzTangential6, 1, 0
219.6 HzTangential0, 2, 3
220.1 HzOblique3, 3, 2
220.1 HzTangential5, 0, 2
221.1 HzTangential6, 0, 1
222.4 HzOblique1, 2, 3
224.9 HzTangential3, 0, 3
225.0 HzOblique5, 1, 2
225.1 HzOblique3, 4, 1
225.2 HzTangential5, 3, 0
226.1 HzOblique6, 1, 1
229.6 HzTangential0, 4, 2
229.7 HzOblique3, 1, 3
230.6 HzOblique2, 2, 3
230.9 HzTangential6, 2, 0
232.3 HzOblique1, 4, 2
234.4 HzAxial0, 5, 0
234.4 HzTangential4, 4, 0
234.7 HzOblique5, 3, 1
237.1 HzTangential1, 5, 0
239.0 HzOblique4, 3, 2
239.2 HzOblique5, 2, 2
240.1 HzOblique2, 4, 2
240.2 HzOblique6, 2, 1
243.4 HzTangential0, 3, 3
243.4 HzTangential4, 0, 3
243.6 HzTangential0, 5, 1
243.6 HzOblique4, 4, 1
243.6 HzOblique3, 2, 3
244.8 HzTangential2, 5, 0
245.9 HzOblique1, 3, 3
246.1 HzOblique1, 5, 1
246.2 HzAxial7, 0, 0
247.8 HzOblique4, 1, 3
249.1 HzTangential6, 0, 2
250.6 HzTangential7, 1, 0
252.7 HzOblique3, 4, 2
253.3 HzOblique2, 3, 3
253.5 HzOblique6, 1, 2
253.6 HzOblique2, 5, 1
253.6 HzTangential6, 3, 0
254.9 HzTangential7, 0, 1
257.1 HzTangential5, 4, 0
257.1 HzTangential3, 5, 0
259.2 HzOblique7, 1, 1
260.8 HzOblique4, 2, 3
261.2 HzOblique5, 3, 2
262.1 HzOblique6, 3, 1
263.4 HzTangential7, 2, 0
264.8 HzAxial0, 0, 4
265.2 HzOblique3, 3, 3
265.2 HzTangential5, 0, 3
265.5 HzOblique3, 5, 1
265.5 HzOblique5, 4, 1
266.2 HzOblique6, 2, 2
267.1 HzTangential1, 0, 4
268.9 HzTangential0, 1, 4
269.2 HzOblique4, 4, 2
269.2 HzTangential0, 5, 2
269.4 HzOblique5, 1, 3
271.2 HzOblique1, 1, 4
271.5 HzOblique1, 5, 2
271.6 HzOblique7, 2, 1
273.2 HzTangential0, 4, 3
273.4 HzTangential4, 5, 0
274.0 HzTangential2, 0, 4
275.4 HzOblique1, 4, 3
277.9 HzOblique2, 1, 4
278.3 HzOblique2, 5, 2
279.5 HzTangential7, 0, 2
280.9 HzTangential0, 2, 4
281.1 HzOblique4, 3, 3
281.3 HzOblique4, 5, 1
281.3 HzAxial0, 6, 0
281.3 HzAxial8, 0, 0
281.3 HzOblique5, 2, 3
282.1 HzOblique2, 4, 3
282.3 HzTangential6, 4, 0
283.1 HzOblique1, 2, 4
283.4 HzOblique7, 1, 2
283.5 HzTangential1, 6, 0
283.5 HzTangential7, 3, 0
285.0 HzTangential3, 0, 4
285.2 HzTangential8, 1, 0
286.1 HzOblique6, 3, 2
288.9 HzOblique3, 1, 4
289.0 HzTangential0, 6, 1
289.0 HzTangential8, 0, 1
289.2 HzOblique5, 4, 2
289.2 HzOblique3, 5, 2
289.6 HzOblique2, 2, 4
289.8 HzTangential6, 0, 3
290.0 HzOblique6, 4, 1
290.0 HzTangential2, 6, 0
291.1 HzOblique1, 6, 1
291.1 HzOblique7, 3, 1
292.8 HzOblique8, 1, 1
292.8 HzOblique3, 4, 3
293.1 HzTangential5, 5, 0
293.5 HzOblique6, 1, 3
294.8 HzOblique7, 2, 2
296.5 HzTangential8, 2, 0
297.4 HzOblique2, 6, 1
299.8 HzTangential0, 3, 4
299.8 HzTangential4, 0, 4

What is a room mode?

A room mode is a frequency at which sound bouncing between a room's surfaces reinforces itself and forms a standing wave. At those frequencies some seats hear a boom and others a dip. Axial modes, between two opposite surfaces, are usually the strongest. The lowest one is the speed of sound divided by twice the room's longest side: about 35 Hz in a room 16 ft long.

How it works

  1. Step 1

    Enter the room

    Length, width and height in feet or meters. The math treats the room as a rectangular box with hard walls, with sound at 343 m/s (air at 20 °C).

  2. Step 2

    Every mode is listed

    Each mode up to 300 Hz, from f = (c / 2) × √((p/L)² + (q/W)² + (r/H)²): axial (one surface pair), tangential (two pairs) and oblique (all three).

  3. Step 3

    The spread is checked

    Modes are counted per 1/3 octave from 20 to 200 Hz for the Bonello check, and the Schroeder frequency is estimated from the reverb time you enter.

Questions

What is a room mode?

A frequency at which sound bouncing between surfaces forms a standing wave. At that frequency, bass builds up in some places in the room and cancels in others, so what you hear depends on where you sit.

What are axial, tangential and oblique modes?

An axial mode runs between one pair of facing surfaces, such as the front and back walls. A tangential mode involves two pairs, and an oblique mode all three. The calculator lists all three kinds and marks each one on the chart.

What does the Bonello check test?

O. J. Bonello (Journal of the Audio Engineering Society, 1981) proposed that the number of modes per 1/3 octave from 20 to 200 Hz should never fall from one band to the next, and that coincident modes are acceptable only in a band with 5 or more modes. Here, modes within 0.5 Hz of each other count as coincident.

What is the Schroeder frequency?

Above it, modes overlap so densely that the room no longer behaves as separate resonances. It is estimated with f = 2000 × √(RT60 / V), with RT60 in seconds and V in cubic meters, so the result is only as good as the reverb time you enter.

Does it work for any room shape?

No. The formula assumes a rectangular room with rigid walls. Sloped ceilings, open doorways, alcoves and soft walls move the real modes, so confirm the results with a measurement microphone.

Privacy: what runs where

  • Every number is worked out in this browser tab. Nothing you enter is sent anywhere.
  • Nothing is stored on our servers, and no sign-up is needed.

Related tools