The sound created by wind turbines is caused by the blade rotation similar to aircraft propellers. Because the rotation rate is low, the frequency is also low, but the large size of many can result in disturbing sound levels, particularly in high wind areas. Most local control is done by advantageous site planning. New Hampshire (Title LXIV, Section 674:63) sets a sound level limit of 55 dB when measured at the site property line, allowing for exceptional events, such as storms. Studies have declared that wind noise can have a negative effect on health.