The back driver wheel

There is a whistling sound that comes from the back tire on the driver side. Do anybody know what I can be.

Bad wheel bearing?

Parking brake. You may have to take off the wheel & rotor to inspect the parking brake hardware. parking brake is an old-fashioned drum brake on the inside of the rotor. They eventually rust out, need adjusting, etc. Sometimes when they fail, it can be real hard to get the rotor off.

The back tires are drums. It happens after I been driving a while. The whistling comes from the back of the car. I don't hear it when I'm driving but when I hold the brakes I hear it.