The chart below shows the distance from the wall that the cancellation effect will be most severe for various frequencies. That distance is always 1/4 of the wavelength of the frequency. At odd multiples of the 1/4 wavelength distance (1/4, 3/4, 5/4, etc.) the sound cancels. The sound is maximized at even multiples of the 1/4 wavelength distance (0/4, 1/2, 4/4, 3/2, etc.) where the reflections add to the original sound. The chart is based on a speed of sound of 1130 feet per second, which corresponds to a temperature of about 72 degrees Fahrenheit.

The formula relating wavelength to frequency is:

wavelength = propagation speed / frequency

For sound at a temperature of 72 degrees, with the frequency in hertz and the wavelength in meters, this becomes:

wavelength = 344.424 / frequency

See the calculator below to compute the speed of sound for other temperatures, or to see the effects of temperature and humidity on the wavelength.

This was page inspired by an article in Tape Op Magazine. Unfortunately the article isn't online, so I can't link to it. To get more information on frequencies and wavelengths and why this cancellation effect happens, you'll have to go to a physics book or search the web.

Note Name	Frequency in Hz	1/4 Wavelength			Reference
Note Name	Frequency in Hz	Feet	Feet & Inches		Reference
A	440.0	0.6420	0	7.705	Standard tuning A
G#	415.3	0.6802	0	8.163
G	392.0	0.7207	0	8.648
F#	370.0	0.7635	0	9.162
F	349.2	0.8089	0	9.707
E	329.6	0.8570	0	10.284	High E-string on guitar
D#	311.1	0.9080	0	10.896
D	293.7	0.9620	0	11.544
C#	277.2	1.0192	1	0.230
C	261.6	1.0798	1	0.957
B	246.9	1.1440	1	1.728	B-string on guitar
A#	233.1	1.2120	1	2.544
A	220.0	1.2841	1	3.409
G#	207.7	1.3604	1	4.325
G	196.0	1.4413	1	5.296	G-string on guitar
F#	185.0	1.5271	1	6.325
F	174.6	1.6179	1	7.414
E	164.8	1.7141	1	8.569
D#	155.6	1.8160	1	9.792
D	146.8	1.9240	1	11.088	D-string on guitar
C#	138.6	2.0384	2	0.460
C	130.8	2.1596	2	1.915
B	123.5	2.2880	2	3.456
A#	116.5	2.4240	2	5.088
A	110.0	2.5682	2	6.818	A-string on guitar
G#	103.8	2.7209	2	8.651
G	98.0	2.8827	2	10.592	G-string on bass
F#	92.5	3.0541	3	0.649
F	87.3	3.2357	3	2.828
E	82.4	3.4281	3	5.137	Low E-string on guitar
D#	77.8	3.6320	3	7.583
D	73.4	3.8479	3	10.175	D-string on bass
C#	69.3	4.0767	4	0.921
C	65.4	4.3191	4	3.830
B	61.7	4.5760	4	6.912
A#	58.3	4.8481	4	10.177
A	55.0	5.1364	5	1.636	A-string on bass
G#	51.9	5.4418	5	5.301
G	49.0	5.7654	5	9.184
F#	46.2	6.1082	6	1.298
F	43.7	6.4714	6	5.657
E	41.2	6.8562	6	10.275	E-string on bass
D#	38.9	7.2639	7	3.167
D	36.7	7.6958	7	8.350
C#	34.6	8.1535	8	1.842
C	32.7	8.6383	8	7.660
B	30.9	9.1520	9	1.824
A#	29.1	9.6962	9	8.354
A	27.5	10.2727	10	3.273	Lowest note on a piano
G#	26.0	10.8836	10	10.603
G	24.5	11.5307	11	6.369
F#	23.1	12.2164	12	2.597
F	21.8	12.9428	12	11.314
E	20.6	13.7124	13	8.549	Low end of human hearing
D#	19.4	14.5278	14	6.334
D	18.4	15.3917	15	4.700
C#	17.3	16.3069	16	3.683
C	16.4	17.2766	17	3.319
B	15.4	18.3039	18	3.647
A#	14.6	19.3923	19	4.708
A	13.8	20.5455	20	6.545

The Speed of Sound in Air

The speed of sound in dry air can approximately be computed using:

V_{sound in air} = 331 + 0.6T_c

where T_C is the Celsius temperature and speed (V_{sound in air}) is in meters per second.

This speed is not correct for liquids or for gases other than air, such as helium or nitrous oxide.

At the temperature	C	or	F
the speed of sound is	m/s	or	ft/s
At that speed:
If the frequency is	hertz
the 1/4 wavelength is NaN m or NaN ft.

At 65 deg. F the speed is 1122 ft./sec., and at 80 deg. F the speed is 1138 ft./sec. -- a difference of about 1.5%. Not really a significant amount for our purposes.