Apologies if this question has been asked before. Whilst travelling on the bus today, I noticed how the driver happened to be listening to music whilst driving. At first, I assumed the music was being played by the passenger sitting across the aisle from where I was sitting (seat directly behind the driver), but once they'd got off, the music persisted and so I concluded it must've been coming from the driver - it did sound like it was coming from the front of the bus! Are bus drivers allowed to do this? (Not that I'd deliberately want to get him into trouble for this, as he was friendly and was doing his job well!) Thanks in advance.