Why do people play music in public through a phone?

Article

http://www.bbc.co.uk/news/magazine-13749313 
An often-seen scene on the streets: teenagers playing music to each other from their tinny-sounding mobile phone speakers, and the people around them being very irritated. It even has its own name: sodcasting. Why do youngsters ‘sodcast’? It seems to be not an act of rebellion, but of marking social territory. The sound of loud music makes young people feel like they own the space. The phenomenon has been around for a longer time, who doesn’t remember being warned by their parent’s to ‘put that noise down’? But the difference is that because of mobile phones teenagers disturb other people in society.

Opinion
Even at schools where kids own laptops (f.e. my internship-school this year), ‘sodcasting’ is a nuisance. They turn their music on their laptops up quite loud once you’re (the teacher) not paying attention, and it becomes a great distraction for the other kids in the same classroom. I think that ‘sodcasting’ is a very natural phenomenon, but teenagers need to be taught that playing loud music in public areas is considered to be anti-social, and can indeed be annoying.