Mr. Dick Bowdler:

The range 107 dB to 110 dB is probably a bit confusing because that is the noise level at source. One would only hear that sound if one were at the source. In the case of a turbine, because the source is so big the noise level is spread around. We calculate what the noise level will be at the receptors, and that is our starting point. There is a fixed decibel level at the turbine itself but that is not the level one would get in communities. One would never get more than 55 dB or 60 dB, even underneath a turbine. Fifty-five or 60 dB would be what would be heard underneath a turbine. The noise level in a quiet rural area quite a distance from main roads at night when there is no wind would typically be 15 dB. During the day in rural areas, there might be 25 dB approximately, provided there are no roads nearby. As soon as one gets close to roads or other activity, there is approximately 30 dB or 35 dB, or even more. In towns, there is a noise level of approximately 50 dB to 55 dB. Notwithstanding what is stated in some literature, the noise level in a quiet bedroom is typically 20 dB in a rural or even suburban area. As stated, a rise of 10 dB is a doubling of loudness. If the normal noise level is 15 dB, 20 dB or 30 dB in a rural area at night, one must acknowledge that 43 dB is obviously a lot louder - by a factor of two, three or even four.