The Ticking Clock Syndrome
Having in the past carried out all the noise complaint investigations for the electrical suppliers in the south west for 15 years I feel I ought to mention my experience with regard to the human psychology of intrusive noise - I called it the "Ticking Clock Syndrome".
Why are people so upset by levels of turbine noise that don't exceed planning criteria?
Current planning law requires the maximum limit of 35 dba in a property. However ambient background levels around here are as low as 20dba and a measured level of just 25dba would be audible,. The ETSU R 97 value of 35dba is the level that might wake you up, but it is far in excess of the level that would annoy you if you were awake or couldn't sleep.
With the Electricity Board we would have carried out remedial work for any noise that was audible, not just if it exceeded some arbitrary level such as 35dba.
What is audible? If you put an alarm clock alongside your bed it is definitely audible. However it only raises the measured sound level by one dba, eg with an ambient level of 20dba it only goes up to 21dba.
The alarm clock is audible but does not annoy you because you put it there! However if your neighbour put something in their garden without your permission which produced exactly the same noise in your bedroom as your ticking clock it could drive you mad! Hence the psychological factor to intrusive noise or "Ticking Clock Syndrome"
Living in a Wind Farm
The Noise of Wind Turbines