Turn Wheel with Mouse. Click Horn to Bleep the Bleeping thing. I say "Bleep" because it sure isn't Beeping with that stuttering in there and it makes me feel like cursing which I can't do and Bleep means Censor so yeah ...
The sounds in Scratch 3 are broken or else the horn would sound better. There is a wait time between plays so you get this irritating extra stuttering noise in there.