My driverside door lock makes a noise whenever I lock my doors. It still locks and unlocks but makes a noise, similar to the kind of noise you get if your roll your tongue to pronounce deep rrrr's.
I think you will have to remove the door panel to see what part of the power lock mechanism is making that noise. I once had a Ford vehicle that made a noise but the power locks still worked. Eventually it stopped working altogether and the power lock actuator had to be replaced.