Non-military helicopter activities include operations for commuting, tourism, offshore transportation, law enforcement, medical response, and information gathering. Helicopter noise is currently evaluated with the same land use compatibility guidelines used for fixed-wing aircraft noise, with sound exposure levels at or above Day-Night Average Sound Level (DNL) 65 dB, judged as a significant impact. However, DNL values produced by helicopters are usually well below this level, even for relatively high levels of helicopter activity. Helicopter noise differs from fixed-wing aircraft noise in many ways. Helicopter operations and the routes they fly are more variable than those for fixed-wing aircraft and often occur at lower altitudes. In addition, the frequency content, sound level onset and decay rates, and duration constitute a unique noise signature that differs significantly from that of fixed-wing aircraft. These distinctions may result in differences in human reaction to helicopter noise versus fixed-wing aircraft noise. There may also be other psychological factors affecting human response to helicopter noise, including detectability and perceived safety and privacy concerns. There is currently a general lack of understanding regarding the relationship between helicopter noise and community response. In 2004, an FAA Report to Congress, “Nonmilitary Helicopter Urban Noise Study,” recommended that “additional development of models for characterizing the human response to helicopter noise should be pursued.” To date, no such work has been done.
Research is needed to better understand the factors affecting community annoyance to helicopter noise.
The objectives of this research are to: (1) determine the significance of acoustical and non-acoustical factors that influence community annoyance to helicopter noise, (2) describe how these factors compare to those contributing to fixed-wing aircraft community annoyance, and (3) develop and validate a research method to relate helicopter noise exposure to surveyed community annoyance.