In recent years wind turbines and small plants for electricity and heat production have been suspected to emit infrasound which supposedly annoys inhabitants living nearby.
Elsam Engineering A/S and Aalborg University have finished an investigation of low frequency and infrasound from wind turbines and small plants for electricity and heat production. Elsam Engineering have made the measurements and Aalborg University have analyzed and commented the measurements in a report). A total of 12 measurements in residences and offices was made. The noise sources were either one or several wind turbines (0.6-2.75 MW) at distances of 90-525 m, or small plants for electricity and heat production (8-260 MW) at distances of 26-700 m.
None of the cases showed levels of infrasound that can be suspected to cause annoyance. However, in several cases there was found low-frequency noise. In some cases, the levels of low-frequency noise were so high that everyone would be annoyed, if they had the noise in their homes. In other cases, the levels of low-frequency noise were so low, that only people with very sensitive hearing would be able to hear it. The levels depended on the distance to and on size of the plant or wind turbine.