ISO 9613 Single Turbine Turbine Noise Propagation

The calculation uses the method of hemispherical propagation which omits directional wind and landform screening effects. It gives a good estimate of downwind noise where the turbine blades are in view.

ISO 9613 ground effects are included.

To use it you need to know the turbine sound power level Lw. This should be available from the developer. The built in figure is typical of 0.5-1.0 MW turbines.

Enter the distance in metres from the turbine, click the `Calc' button. To start again, click `Clear'.

Turbine sound power dB   Hub height m

Distance m

Subtract: Dispersion Ground Atmosphere Add:

Net noise dB.

The Meaning of Decibels

The Decibel (dB), one tenth of a Bel, named I believe after Alexander Graham Bell, the inventor of the telephone, is a unit of power and sound level.

It can seem confusing because it is a nonlinear scale. Unlike the lengths, weights and temperatures with which we are more familiar, twice the number of decibels is a lot more than twice the amount of noise. In fact, every ten addtional dB means twice the amount of noise. The table below should give some idea of what different values mean.

Sound Level, dB Example
140 Threshold of pain
135 Jet engine at 25m
125 Jet takeoff at 100m
110 Rock group
100 Unmuffled pneumatic drill
85 Busy street traffic
60 Normal speech
43 ETSU-R-97 outdoor nighttime max
40 Living room
35 ETSU daytime lower fixed limit
30 WHO bedroom limit
25 Recommended bedroom level
20 Typical rural nighttime
10 Practical limit of hearing
0 Theoretical limit of hearing