It's hard to diagnose without hearing the noise, but if you're sure that it is not the brakes, it could be dirt/sand/rock in the brakes. If you're hearing the sound all the time (even when not...
If you are on a slippery road or just push the brake as hard as you can, that odd grinding feeling is probably your anti-lock brake system. The pedal will feel like it is grinding under your foot,...
Is it from the wheel? If so, then it could be numerous of things: worn hub bearings, worn brake pads/shoes/rotor, faulty drive axle...listen carefully and take you car to a certified mechanic!