If you have a room above a garage and the opener can be heard through the floor, here's a tip that will make it a lot quieter:
Hang the opener on short (but strong) rubber straps instead of mounting it directly the ceiling. The rubber will absorb the vibration and lessen the noise transmitted through the joists.
I used a 3 ply material similiar to a tire (specifically a brake pad from a Soap Box Derby car!) and the reduction in noise was amazing.
Enjoy!