Brake noise is caused by high frequency vibration,this is why some cooper grease on the back of pads and on the anti rattle shims stops it,it soaks up the vibration.

Check the fit of the pads also at the bottom where they sit on the caliper and at the top,sometimes the pads back plate has a rough edge instead of smooth and this causes them to stick or pass noise on.

The disc can also pass noise if there is no copper grease or equivalent between it and the hub.