I think definitly hearing since, when you see something, true it can be really scary but at least you are seeing the danger and react acordingly, if you only hear, sure you can think "oh it's nothing just noises" but from my experience with just a sound if I'm willing I'm able to imagine something that really makes me scared. I did this a couple of times to test it out and to this day sometimes when I'm trying to fall asleep I'll do it to see how far my imagination runs.
For instance you hear a simple bump in the dark. Ok just something falling, something giving in to weight a simple crack from the computer whatever, you can dismiss it at that or, and if you want you can try it, if you let your imagination run wild you can simply think, that was an accidental noise by something that's standing right beside my bed.
Seriously hearing without seeing is scary as hell.
For instance you hear a simple bump in the dark. Ok just something falling, something giving in to weight a simple crack from the computer whatever, you can dismiss it at that or, and if you want you can try it, if you let your imagination run wild you can simply think, that was an accidental noise by something that's standing right beside my bed.
Seriously hearing without seeing is scary as hell.