[nugi]

How so? The only difference is prop size, you seldom hear the motors of helicopters. Only the blade chop.

[Retric]

They only use vertical takeoff to get up to speed or when landing. In flight it's just as loud as a normal single engine aircraft which are generally quieter than a car at ground level.

[Kluny]

Yeah, but that's exactly when the noise is most annoying for everyone else.