The procedure to calculate the wavelength of sound (that is, the distance a sound waveform travels between its peaks) is dependent on the pitch of the sound and the medium the sound travels through. In general, sound travels faster through a solid than a liquid, and sound travels faster through a liquid than a gas. A sound wavelength calculation requires that you know the speed of sound through the specific medium and the pitch of the sound. Once these two variables are known it is just a question of dividing the speed of sound by the pitch to obtain the wavelength of sound.
Determine the speed of sound for the specific medium the sound travels through. Look up in a speed of sound table the speed of sound for the medium. Look in a speed of sound liquid table if the sound is traveling through a liquid such as salt water or fresh water. Look in a speed of sound gas table if the sound is traveling through a gas such as air or helium. Look in a speed of sound solid table if the sound is traveling through a material such as cork, concrete or wood.
Determine the pitch of the sound. Remember that the frequency, or pitch of a sound, is the number of times a sound pattern repeats itself per second, measured in cycles per second. Use a sound frequency meter to measure the pitch or estimate the pitch. Consider that the human ear can hear sounds in the range of 20 cycles per second (low bass-like notes) to 20,000 cycles per second (high flute-like notes).
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Calculate the wavelength of the sound. Divide the speed of sound determined in Step one by the pitch of sound determined in Step 2.
Consider that the temperature of the medium will also affect the speed of sound. If you want to calculate the speed of sound in air for different temperatures, you must use the speed of sound for the specific air temperature. There are published tables just for this purpose.
There are other variables besides the medium that will change the speed of sound. The speed and direction of the wind will also change the sound speed and the wavelength. In water, the speed and direction of the current will also alter the sound's speed and the sound's wavelength.