If the right rear wheel of an Acura makes a funny sort of metal windy noise when the car begins to run what could it be?

I just had the same thing happen to my car, I was worried that it was a bearing as well however it was only the brakes. As the suggestion below says it's probably the brake pads wear indicator. I have never heard a wear indicator make that much noise before. I didn't even want to drive it because of the racket it was making.

It's probably a wheel bearing. It might be the CV joint, too.

It can also be a small emergency brake pad inside the disk brake, rear only? The drum brake system inside the rear disks rub with the with disk when driving.

If it is a low pitched rumble/growl then it is likely a wheel bearing and if it is a high pitched squeal (similar to nails on a chalk board) then it is almost certainly your rear brake pad's wear indicator.