I live next to an airport. I've been around planes of all types and sizes and helicopters all my life. I've worked at airports refueling and servicing airplanes and helicopters for 6 years. You can hear helicopters coming from several miles away and going for another mile. And if they start circling over your neighborhood for more that 30 seconds, everyone in the neighborhood will come out and wonder what the heck is going on.
Surprisingly, it is NOT because of the noise level. Helicopters aren't that different in sound levels than airplane engines. It is because of the rotor slap that helicopters make. Its highly annoying, whereas airplanes and drones do not create rotor slap.
Read this FAA study on helicopter noise. Its very interesting.
http://www.faa.gov/regulations_policies/policy_guidance/envir_policy/media/04nov-30-rtc.pdf
In particular, this from section 3 page 7...
3.5.1 Heightened reaction to helicopter noise
Typical of heightened reaction to helicopter noise is the experience of the U.S. Navy at Miramar
Marine Corps Air Station. Miramar had long been a naval air station famed for its Top Gun
School and its F-14 Tomcats. But with Top Gun moving to Fallon, Nevada, and the Tomcats
being assigned to other bases, Miramar was turned over to the Marine Corps in 1997, which
brought in helicopter and F-18 operations. Almost from the beginning, residents have
complained about noise and pollution and expressed concerns over possible helicopter crashes.
Yet, the noise contour map is not significantly different from when the F-14 aircraft were
operating.51 In addition, the contribution of helicopter operations to the overall DNL is much
less than that of the F-18 operations.
An example of heightened reaction to helicopters at a general aviation airport was published by
Schomer (1983b).52 At an airport where the noise exposure was dominated by fixed-wing aircraft
and with less than two helicopter operations per week, 7 percent of the people exposed to a DNL
of 66 dB reported themselves to be å¡ighly annoyed by helicopters. A 1982 study from the
United Kingdom also found a heightened reaction to helicopter noise.53,54,55 In the community of
Lower Feltham, the contribution of fixed-and rotary-wing aircraft to the overall noise exposure
was about equal. However, the percentages of people who considered helicopters more
disturbing than fixed-wing aircraft were 2 to 2.5 times as large as the percentages that considered
helicopters less disturbing. In the communities of Esher and Epsom, where the numbers of
helicopters and a fixed-wing aircraft were about equal, the disturbance due to helicopter noise
was 2.5 times as large as that due to fixed-wing aircraft noise. People were more annoyed by the
helicopters even though, on average, the fixed-wing aircraft were 5.0 dB louder.