not all zoos like heavy music ... but yeah, it does seem like the vast majority do.
i'm still disappointed there aren't more options in the poll.
just one voice for quieter music. i don't _hate_ louder music, but i have to be in the mood for it. music with a mix of synths and "normal" instruments is usually my preferred -- stuff like radiohead, for example. my tastes swing away from the middle of that spectrum, though -- sometimes i like stuff that's all synths (i grew up in the 80s loving synthpop like howard jones, thompson twins, tears for fears, the police, peter gabriel, etc.; also electronica/ambient/techno stuff, particularly the future sound of london, the orb, orbital, underworld, aphex twin, etc.), and sometimes i like stuff that's all more typical rock instruments (drums/guitar/bass; stuff like R.E.M., toad the wet sprocket, david sylvian, talk talk, etc.). all that said, it's the mellow stuff that tends to grab my attention more than the louder stuff, though.