>>>So, how about a nice cup of STFU?
>>
>>So, were you an ACORN recruiter too? If so, you might want to start looking for those black
>>Suburbans or Tahoes. The black helicopters actually do make a swooshing soung too....
>
>John, this is Maine. _Everyone_ drives pickups, even for black ops.
>
>And can you give me some tips on how to tell the difference between black helicopter and medical helicopter sounds? I live right near a hospital, so this could be important information to have...


Each helicopter has a distinctive sound. The sound also is different when flying over land, water, and around mountains and different land formations.

You can start here:

http://www.helis.com/sounds/

However, there are some modified and specially designed helicopters which deploy mechanisms to reduce the noise footprint and unless you live near a base which has them (or somewhere they are deployed), you're unlikely to have the opportunity to hear them.

As long as the helicopter you see or hear is not a 'black helicopter', I wouldn't worry :o) If however, you see a black helicoper, but hear no sound, well then, duck and cover! :o)