They find you by hearing you. If you tip-toe across the area, they won't find you. If you run, they will find you due to your feet making all the noise.
Typed on my Wii...
No, this is the deal. When you approach a Redead slowly, they won't attack or shriek. They can hear your footsteps. Boots are kinda noisy. When you go slowly, they won't attack; on the other hand, quickly means attacking...