Camry Forums - Toyota Camry Forum - 2009 camry low frequency brake noise

Hi, I'm new here, I have a 2009 toyota camry le 2azfe with 135,589 miles on it and despite having the front and back brakes both looking just fine per my mechanic, I continue to hear a low frequency noise at times similar to the one from this video: https://youtu.be/d_uxPXNGTos

I usually only hear the sound when backing up, slowly, and turning, like when parallel parking. The sound is louder if there is or has been moisture in the air like rain, snow, fog, condensation. Also it seems like the sound is more prevalent in the colder months. It is very annoying. When I first complained of this sound to my regular mechanic in December 2019 they did a rear brake job and the sound continued after several return visits. I went to another shop for a second opinion and they said it was intermittent or sticking calipers, they replaced the rear calipers, and the sound went away for several months, until recently. My regular mechanic looked again last week at the front and back brake areas and supposedly the backing plate was making contact with the rotor on one wheel. They claimed to have fixed the issue but the squeals continue. I'm thinking maybe I need ceramic pads with the weights on them that minimize the noise. Any ideas or thoughts, thanks!