SpeedAir is a free calculator for live sound engineers to calculate to speed of sound and atmospheric frequency attenuation.

Time Delay

The time delay for sound to reach a distance. This is the delay from your main speakers to the audience or a delay/relay speaker.

SPL with Distance

Sound levels decrease according to the inverse square law. This gives an indication of the loss is SPL over a distance.

Air Attenuation

Frequencies are attenuated due to atmospheric conditions. The app calculates the attenuation in decibels (dB) according to distance. The high frequencies and attenuated more and this effect is most noticeable 2kHz.


The speed of sound affects the wavelength of frequencies. If you are setting up sub arrays, then the wavelength is important. The app calculates the half and quarter wavelengths.

Half Wavelength

Your subs should be no more than this distance apart to avoid the interference patterns of power alleys and valleys.

Quarter Wavelength

You should space your subs this distance apart when using gradient or end-fire arrays.

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