Questions

Sound is measured in decibels (dB). The table below gives useful comparative sound levels.

The sound at the base of a typical modern turbine is approximately 50dB, the sound 500m downwind is approximately 30dB and upwind approximately 20dB. Existing background sound levels will occur ranging from just the sound of the wind itself to complex urban sounds. Typical rural background noise is between 20 and 40 dB. Government guidance (DTI noise working group) requires sound from turbines to be no more than 5dB above background sound levels with a minimum of 35-40dB in the day and 43dB at night. The Environmental Protection Act empowers residents to pursue individual action even if these conditions are met.

Modern wind turbines are surprisingly quiet because of specified design of the blade edges, heavy insulation of mechanical items and damping of moving parts. With careful planning it is rare for noise to be a nuisance. Issues might arise where there is a very low background noise level, such as in valleys without any wind noise. Detailed noise assessments can be conducted to measure the background noise and then use computer modelling to forecast the sound from turbines to ensure there is no unreasonable noise. The environmental benefits of windpower should not be at the expense of unreasonable local noise nuisance.