[gerdesj]

I live near a helicopter factory and when the spinning towers are in use, you hear all sorts of auditory patterns as you move around the town. When they are test flying - similar and the Police have one and there is an air ambulance too. My Dad's other staff car in the '80s was a Gazelle and in the '70s he whizzed around in a Sioux. I've seen and heard a lot of helos!

I have absolutely no doubt that with some funky signal processing you can do all sorts of things.

[morkalork]

And here I thought living behind a few garages that rev engines all day long was disturbing

[gerdesj]

Its much less disturbing than living under a flight path to an airport. I actually like the sound of a helo - its variable and interesting, as is a piston powered fixed wing aircraft.

Mind you I also lived near RAF, USAAF and Luftwaffe bases back in the day and several flights of Phantoms, Starfighters, Jaguars and Tornadoes and the rest can make quite a din. Phantoms were pretty huge engined beasts with minimal effort made for noise reduction. A "finger four" lighting up their after burners to gain altitude really fast is ear splitting.