In air at 20 °C, sound has a speed (c) of about 344 m/sec ( = 1238 km/h = Mach 1 ). On the basis of this you can calculate the corresponding wavelength λ (lambda) for each frequency f. This wavelength is equal to the distance the sound travels when one complete vibration has occurred. |
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The speed of sound changes clearly with temperature, a little bit with humidity − but
not with air pressure (atmospheric pressure).
Sound can also propagate through metal, wood or water, for example. The speed of sound is different, the stiffer the material, the higher the speed. In gases lighter than air, such as helium, the speed of sound is also higher, which is why your voice will sound higher if you have inhaled helium gas from a helium balloon. In air the speed is about 344 m/sec, in steel the speed is about 5800 m/sec, in rubber 60 m/sec, in wood (depending on the type and in which direction) +/- 3800 m/sec, in pure Helium gas 1007 m/sec. The speed of sound depends on:
With the calculator below you can see the effect of temperature and humidity. Air pressure has virtually no influence! You can also see that a higher temperature results in a higher speed. Approximate formula: c = 20 * √ (273 + T) T is the temperature in Celsius, c is the speed of sound in meters/sec. |