Yes I experience it, but I don't turn my sound off. If I don't touch my phone for an entire day and just let it sit on my desk, i'll lose maybe 2-3% in 24 hours. If the phone's not doing anything, the battery is not going to drain that much.

 

While idle, your phone should do that with sound at full blast or not. Just how it works.

 

With good signal, that is ;-)