I hope that's a joke because a) you shouldn't be using your air horn in town, and b) blasting an air horn that close to people in a crosswalk could actually permanently damage their hearing.
Play nice!
For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
~ Carl Sagan
My air horn isn't anything special (and the regular horn is squeaky-toy embarrassing)...I only use it when someone stops in the middle of the crosswalk for no reason.
My uncle thinks he made a guy crap his pants in Pittsburgh. The guy crossed halfway...answered his cell phone (a novelty at the time), and started talking in the middle of the road. Several people and my uncle honking regular horns got no result...so my uncle pulled the air horn wire. His Kenworth had three air horns. Three locomotive air horns. Fed by two dedicated air tanks (scavenged from junk trailers) and large-diameter air lines. The guy jumped so high he fell on his ass.
I had one of those 'portable' boat horns powered by a small compressed gas can on my commuter bicycle. The got attention from car drivers right-turning in front of me.