I know it sounds dumb, but have you had the front wheels off lately? sometimes if you have the wheels off, or working on the front brakes
you can bump the dust shield, and that can be contacting the rotor, but ever so slightly.. and then when you apply the brakes it lessens the
vibration, as well as slows wheel speed down, slowing the noise down... I would check the easy stuff first, dust shields, no debris or anything
contacting the brakes... etc..