Estimate how a point sound source level falls off with distance in a free field for noise assessment and plant-boundary prediction.
未考虑空气吸收和地面效应。
| Item | Formula | Source / Standard |
|---|---|---|
| Point source | Lp = Lw - 20log10(r) - 11 | ISO 9613 |
| Double dist. | SPL -6 dB | inverse square |
| Unit | dB(A) | sound level |