[csaxon]

I would start by checking the front brake pads/rotors since the sound occurs when you apply them. You may simply need new front brake pads.
Do you do your own car work?
I would also check the cv joints (look at the shaft between the engine/transmission and the wheels. The rubber boots on both ends and the wheels) and see if they're torn or leaking grease.

If you raise the wheels off the ground you can manually turn them and perhaps hear and feel the area where the grinding is coming from.