wooooooooooooooop- weird sounds from my car

[w123fanman]

So in my 190D, I have lately been hearing this weird noise. It's very loud and almost sounds like one of those noise stick toys https://www.youtube.com/watch?v=GdNJfbPnlQ8"]https://www.youtube.com/watch?v=GdNJfbPnlQ8
But more human. It's like my car is talking to me.

Actually not like its talking to me, but its like a wooooooooooooop with the pitch trending upward. Seems to only happen when coming to a stop on a hill while going down it.

Any ideas what this could be?

I'm wondering it it is brakes related because my MC is really about as close to being time to stop driving the car in fear of no braking power at all (I'm only driving my car once every week or so just so it isn't sitting without being driven at all).