Is Low Frequency Noise a Problem for Wind Turbines?
Source: Neil Kelley, U.S. National Renewable Energy Laboratory 1) Because of the low rotational rates of the turbine blades, the peak acoustic energy radiated by large wind turbines is in the infrasonic range with a peak in the 8-12 Hz range. For smaller machines, this peak can extend into the low-frequency “audible” (20-20KHz) range because of high rotational speeds and multiple blades. 2) The levels of infrasound radiated by the largest wind turbines are very low in comparison to other sources of acoustic energy in this frequency range such as sonic booms, shock waves from explosions, etc. The danger of hearing damage from wind turbine low-frequency emissions is remote to non-existent. Generally there little acoustic energy much above about 4000 Hz so ultrasound is not a problem. 3) Impulsive noise generation is generally confined to turbines whose rotors operate downwind of the support tower (downwind machine). In this case, impulses are generated by the interaction of the aerodynam
