I noticed that my sister usually sings along to the songs that she knows while she is playing Guitar Hero. I have also caught myself humming (because I don't know the lyrics) along to many of the songs that have a melody that I am familiar with. So what percentage of people sing along to Guitar Hero songs ( in your opinion)
I would say its around 30% of people. I do it (for the songs that I know) and my sister does it as well. MY guess is that people would only sing on easy or medium because those are the easiest settings, but when playing hard or expert you need to concentrate more on the notes so no one sings when they are on hard or expert.