When stepping on the brake, does pull to one side? Is there vibration to your steering wheel? Did you change both front rotors and did you see any heat discoloration on your rotors (dark blue spots) did you bleed all four brakes to completely clean out the brake system? If all checked out ok then next thought is to check wheel bearings and tie rod joints. Your best clue is to discover where the sound is coming from.BTW, do you have an automatic or manual?