I cant play worth shit when i have music on. Some good headphones gives a big advantage as you can hear footsteps and what not.
There are some reasons for music. I just want to play and I'm not looking for winning. Or It's tdm and my team mates are as loud as a herd of mammoths. Or the server's too crowded. Or I have a headache from all that noise. Or ...
As said before imo another prob would be accents.
But how does this work anyway? Does it require certain software (-> mac?), etc...