It's strange but when I am at work (office) I am not one of the headphone brigade. That is the type who are locked away in at their deck oblivious to me or the boss screaming for their attention.
For one I can't concentrate and find it a distraction. However, when writing the next 'Tales of the Urban Explorer' it can be good to listen to some deafening music occasionally.
New music requires my concentration and simply won't 'sink in' if I am occupied and writing about some apocalyptic place I have visited.
However, a listen to the excellent 'In Absentia' at 120db does help. Imagine a truly heavy song that turns into a regular melancholic mid-tempo pop song and your listening to 'Blackest Eyes'.
Metal is metal, and generally stays there, but not with Porcupine Tree. I love how this band surprise people, and are difficult to categorise.