Note 1 to entry: In equation form: $N_{\text{PL}}=-\text{10lg}\left({\left|H\left(f\right)\right|}^{\text{2}}/d_{\text{0}}\right) \text{dB}$, where $H\left(f\right)$ is the transfer function from source position $x_0$ to receiver position $x$. The transfer function, $H\left(f\right)$, has dimensions of inverse distance (the value of reference distance $d_0$ in the denominator of the logarithm argument in the equation is 1 m²).

Note 2 to entry: Propagation loss is defined for an equivalent monopole point source (where the source is treated as a point source of sound).

Note 3 to entry: This definition of propagation loss is consistent with that of ISO 18405, which is more generally applicable and valid for a finite source.

Note 4 to entry: The reference value for propagation loss is 1 m².

Note 5 to entry: This note applies to the French language only.