*2.3.5 Atmospheric absorption* Aatm

The atmospheric absorption refers to the attenuation of sound due to traveling through the air along a distance *d*. According to [5], it should be calculated by applying Eq. (10).

$$A\_{atm} = \frac{a \cdot d}{1000} \tag{10}$$

Where:

*d*: Distance in meters from the source to the receiver

α: Atmospheric absorption coefficient, expressed in dB/km in each octave band.

α depends mostly on the frequency of the sound, the temperature, and the relative humidity of the air. Atmospheric absorption should not be greater than 15 dB at any octave band.
