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'.
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|
|100||Unmuffled pneumatic drill|
|85||Busy street traffic|
|43||ETSU-R-97 outdoor nighttime max|
|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|