# Air absorption attenuation with humidity and frequency

How much high frequency is lost over long distances?

If we calculate the loss of sound pressure level as we go away from a loudspeaker using the inverse square law (-6 dB per doubling of distance), we will get a theoretical value that is valid for short distances but not for longer ones. This is due to air absorption. This is greater with

**dry air** than it is with

**high humidity** (water is a better conductor of sound than air). The curves evidence this behaviour at 30 m (100 ft).

Also, air

**absorption varies with frequency**. It is well known that the very high frequencies are the first to go at long distances. Curves for different frequencies are therefore presented.