Front brake make noise

When I slow down 99 maxima to < 20mph and press the brake, I can hear "Ong" "Ong" noise coming from the front left wheel. I checked the brake pads which still have more than 50% and the rotor is OK(?) Should I change my rotor since it already has 120K miles? My rear rotor was changed 3 years ago. Is $29.99 rotor from Autozone OK?

Thanks,

maxl1961

Noise source may be also bearing and/or axle; possibly mildly warped disc.

Troubleshootin: If u swap your left front rotor to right, the noise will move with it - if its the source.

There are no accident dangers if metallic dust was not seen, no free play on bearing/axle was detected: the noises from wheel may increase to a level where ppl will start looking at your vehicle - before any hazard. Mildly warped disc is no danger either. I guess I'd keep on drivin.

Thanks,
You remind me it could be the driver side bearing. When I removed my left draft, I had difficulty to take it out. The draft was replaced since its threads was damaged because of using the hammer. The bearing could be damaged a little bit and it could became worse by the time going. I may replace the rotors and bearing when I get time. Thanks,

maxl1961