I'm the kind of person that if any one is watching TV or listening to music with me, they'll tell me to turn it up because it's too quiet. For example, the sound on my TV goes up to 100, but a majority of the time it will never go above 8, except for a sports channel I watch that has low sound, then it goes up to about 20. My iPod never really goes above 40% when I'm listening to music, but I also have very old earphones (with newer ones I would probably be at about 25%).
My sister is the opposite of this, though, as she thinks that it can never be loud enough. We always joke that she'll lose her hearing before she turns 50, but it honestly wouldn't surprise me if she did.