I'm polishing one of the numbers in my score for a musical theater piece. I'd like to include the sound of a train whistle. Not having a sample library of that percussion "toy", I want to try to simulate it with two of the reeds. I have a picclo, flute, and Bb clarinet available at that time. I suppose I will need two of those instruments, but I am not sure what interval to use.
Obviously, I'm looking for something that immediately says "train whistle" to the audience. However, there will be other clues (dialog and reactions of other characters) to indicate that a train is pulling out of the station. The rest of the orchestration also helps suggest this (clanging bells, shaken marachas to suggest steam, etc.) I'm satisfied with the effect except for the fact that I think it needs the whistle and I don't want to add another instrument to be used for just this one instance.