That's a great point. I heard high pitched sounds work best. Nothing is more annoying and funny than that pig commercial where it keeps screaming "wheeee", maybe that would be best to play that loud on your phone.Maybe just record yourself screaming. Then you can count for twice when it really counts.
Make signs that tell people to download free air horn apps on their phones. Remind the person on your right and ask them to tell the person on their right so word will get to everyone.This is brilliant
When air horn apps are outlawed, only outlaws will have air horn apps