Low frequency sound is in the range of 20 – 200 Hz, and infrasound is in the range of < 20 Hz. They are perceived as a mixture of auditory and tactile sensations and can be caused by natural or manmade sources. Some natural sources include waves or simple the weather; heavy machinery and many household appliances, or even road noise are also sources of low frequency sounds. We are constantly exposed to sounds in these ranges in our daily lives. Infrasound is emitted from modern wind turbines (and many other natural and man-made sources), but is NOT a problem because emissions from wind turbines are below the level of human perception. There is no scientific evidence that infrasound below the hearing threshold produces physiological or psychological effects. Furthermore, field measurements and studies on North American wind farms indicate that infrasound levels are below human perception levels at distances greater than 100 m from turbines.