what does it mean, when you have a noise that kind of sounds like a loud horn when you back up

I have had the car for 10 years :-) it just started this about a month or so ago when it got really really cold.

Sounds are just about impossible to diagnose over the internet. Can you tell where the sound is coming from?

kind of sounds like an owl with laryngitis. I don't know how else to explain the sound it makes when I back up. It only last for a couple minutes while I'm backing up, after I get going and take off it's not something that keeps on making noise.

it must be something coming for my brakes because it only happens when I'm backing up, like out of my garage and I step on the brakes.

We are posting at the same time. I think you have squeaky brakes.