Well - it wouldnt be very free if your neighbors were imposing their noise on you either. The laws about noise control more than anything. It mentions swearing, shouting and fighting as well as amplified music. I personally have never felt the need to swear at the top of my lungs after 11pm - some people need it spelled out for them.
Its a by-law which means the cops wouldn't enforce it - some guy from the city would come out and maybe after a few incidents they would consider levying a fine!