Which Noise Signature ?
There are many different Noise Signatures that Helicopters make when approaching straight and level - steep turning - etc.be it from Main or Tail Rotors 2 -3 - 4 - or multi bladed types.
Would anyone agree that the MD 500 has one of the best making you feel great to be hands on with, or might it be the SA 341 ?
Some might say they could tell from the noise it made as to who was flying it !