A time line of wind turbine infrasound and low frequency noise.

The existence of infrasound and low frequency noise has been known for several decades.  The subject was studied extensively by a joint NASA/DOE/SERI effort beginning in 1979 and continuing for almost a decade.  The wind industry did not pick up the subject until 1995. A time line showing the significant milestones is well developed here:  Infrasound/LFN Timeline