I hear this (attached sound clip) when inching forward while at a stop light or stop sign (back of a line of cars). Its definitely emanating from the front brakes. Is this a concern, or merely an annoyance? Can it be remedied?

I'm gonna have access to a lift soon (to replace my O2 sensor), and I thought I better address any and all issues while I have the opportunity ...

 

Recently was my problem. Your pads have glazed over. You need to remove the pads and sand with emery paper the glaze off or use a sander to do so. I fouknd that one day my brakes failed completely due to this problem as heat built up releasing a gas the came between the pad and the disk. Just take care of it sooner than later.

 

Check the thickness of the brake pads. The little metal tab that makes a screetching sound when the pads wear down, can make any number of strange different sounds when it first just begins to touch the rotor. After the pad wears down a little more, then they start screetching.