Brake pads generally have a wear indicator which consists of a small aluminum arm that is comes off the pad base and points down toward the rotor surface. When the pads start nearing the end of their life, they become thinner. As this progresses, the indicator comes into contact and drags against the rotor to give you a squealing sound whenever the wheels are turning and car is in motion. It doesn't matter whether brakes are depressed or engaged. Sounds like it just needs a brake pad change. That is, if... the sound is coming from the front of the vehicle. Could be a few different factors, but I'd say this is likely the culprit.
The most common cause is slipping belt
When the wheel and the tire rub together.
main shaft bearing
you probly have a belt slipping, a can of belt dressing should stop the sound
Loss of traction. The loss of traction can come from braking too quickly. Or accelerating to quickly
Wheel hubs or bearings or could be the CV shafts.
idler pulley. Change it now before the serpentine belt breaks. Hard job to do I think?
One clunk when accelerating (but now repeated clunks) and another when braking can be caused by broken motor mounts.
it is possibly your calipers and or rotors.
A worn belt will cause a squealing noise. The squealing noise is caused when the belt slips. Tightening the belt will temporarily fix the problem.
Check the belts. The most common cause of squealing is a worn or loose belt on the front of the engine.
Pull the transmission pan. If there are any metallic shavings it is transmission related. That was the case here.