ORIGINAL: Arthur P
You don't say what bow you're talking about, what the draw weight is, or what your arrow weight is. That kind of information would be helpful. But as a rule, if you're shooting the bow at the low end of it's draw weight range it will be noisier than if you were shooting it at the peak end. Also, the lighter your arrows the noisier the bow will be.
I would have to agree with Arthur P,
try going to a heavier arrow or increase your draw weight if you can.