we did a whistle for our pneumatic actuated claw... We could hear it from the 3rd floor at the Edward Jones dome...
the whistle was made of tubing with an angle cut in it, in the solenoid exhaust, and weights only a few grams.
You can here it here when our claw opens -
http://www.thebluealliance.com/match/2015qcmo_qf1m4
Edit: it does not make 118's Bshooo sound, but more of a Tchoo/Tchuiii