ISO 9613.2 Ground Effect

**Strutt|Environmental Noise|ISO9613.2 Ground Attenuation** inserts attenuation (dB) into the active row of the worksheet.

Input required is source and receiver heights, source to receiver distance and ground factors.

Ground factors to be used are:

**Hard ground:** 0

**Porous ground:** 1

**Mixed ground:** 0 - 1

The ground effect is calculated by separating the distance between the source and receiver into 3 regions as:

The total ground attenuation for each octave band is calculated as:

`A_(gr) = A_s + A_r + A_m`

Where,

`A_s` is the source region attenuation

`A_r` is the receiver region attenuation

`A_m` is the middle region attenuation

`A_s`, `A_r` and `A_m` are calculated using:

Nominal midband frequency, Hz | `A_s or A_r`*, dB | A_m, dB |
---|---|---|

63 | `-1.5` | `-3q`** |

125 | `-1.5 + G xx a'(h)` | `-3q(1 - G_m)` |

250 | `-1.5 + G xx b'(h)` | |

500 | `-1.5 + G xx c'(h)` | |

1000 | `-1.5 + G xx d'(h)` | |

2000 | `-1.5(1 - G)` | |

4000 | `-1.5(1 - G)` | |

8000 | `-1.5(1 - G)` |

Notes:

`a'(h) = 1.5 + 3.0 xx e^(-0.12(h-5)^2)(1-e^(-d_P//50)) + 5.7 xx e^(-0.09h^2)(1 - e^(-2.8 xx 10^-6 xx d_P^2))`

`b'(h) = 1.5 + 8.6 xx e^(-0.09h^2)(1-e^(-d_P//50))`

`c'(h) = 1.5 + 14.0 xx e^(-0.46h^2)(1-e^(-d_P//50))`

`d'(h) = 1.5 + 5.0 xx e^(-0.9h^2)(1-e^(-d_P//50))`

-------------------------------

* For calculating `A_s`, take `G = G_s` and `h = h_s`. For calculating `A_r`, take `G = G_r` and `h = h_r`. See 7.3.1 (ISO 9613.2) for values of G for various ground surfaces.

** `{:(q = 0 , when \ d_P <= 30 (h_s + h_r)),(q = 1 - (30(h_s + h_r))/d_P, when \ d_P > 30(h_s + h_r) ):}`, where `d_P` is the source-to-receiver distance, in metres, projected onto the ground planes

References:

- ISO 9613-2 Acoustics - Attenuation of sound during propagation outdoors - Part 2: General method of calculation, pp5 - 7

Comments or suggestions to strutt@arup.com