While listening to my ipod, I have to have a hand on the volume constantly, because I'm always turning it up and down without noticing. It will be too loud and someone's walking by me and I'm afraid they'll hear, so I turn it down, but then it feels too quiet and I like the part of the song, so I turn it up... I don't notice myself because it's half subconscious, until I need to take my hand away and get an overwhelming urge to adjust the volume within seconds.