Low-frequency sound explained
At the adjacent wind farm N33 around Veendam and Meeden, hum tones were found by means of a so-called spectrum analysis. These hums are low-frequency noise. That is sound with a frequency lower than 125 Hertz.
The lower the frequency, the further the sound travels and also the louder the sound must be to be perceived. Sound below 20 Hertz is in principle inaudible to humans, but can be felt.
For many people, low-frequency sound is not immediately perceptible. But people who do observe it can suffer greatly from it. Some also experience health problems, such as insomnia, stress and heart problems.
No specific statutory standards for low-frequency noise apply to wind turbine noise. This specific legislation does not yet exist for other humming sounds either.