Sounds from the crowd in big fights...

I've got a question for all of you guys that have been to big fights like in Staples Center,Madison Square Garden,The Mandalay Bay Center, etc. etc. What the hell are all of those weird ass back ground noises in big fights? Yes, i know it's the crowd cheering and such, but there's always gang whistles (like Crip whistles and Sureno Whistles and such) and then like in the Shane Mosley vs Miguel Cotto fight there's like a banshee getting raped with an ice pick in the background and what the hell are all of these noises? do people really bring like noise makers and some shit to these fights? I ask because i've never been able to afford to see a live boxing match in a major venue. I guess people are douches no matter how much money they pay for tickets at major events...?!!