Atténuation par les obstacles

Top-diffractions with ISO-9613:

In this standard, the barrier attenuation includes (for top-diffractions) a correction $mathematical expression$ for meteorological effects (see [ISO-9613-2]): this corrects (reduces) the barrier attenuation to better correspond to propagation-favorable conditions (downwind or temperature inversion conditions). [Wind-speed and temperature gradients cause "sound-rays" to be curved downwards.]
The interpretation used for a barrier on an acoustically-hard ground ( $mathematical expression$ ) is in agreement with [ISO/TR-17534-3].
The second edition of this standard [ISO-9613-2:2024] [available from SLIP'25] updates the treatment of downward-curved rays under favorable propagation conditions in barrier-attenuation calculations. See ISO-9613.

For more information, see [ISO-9613-2].

Side-diffractions with ISO-9613:

See Lateral diffractions (ISO-96113).

Note on the 2nd edition of ISO9613

For comments on barrier-attenuation in the 2nd edition of ISO9613, see ISO-9613.