craiglowsubaru

Hello all, This is my first Subaru so I'm sure there is a lot I don't know. I search for the answer before posting so please forgive me if I missed it. When Car reaches 45 it makes a chirp or squeal sound just once. I purchesed this 2 m ago from a local used car dealer. I took it back to them and they diagnosed the serpentine belt as the problem. Problem has not changed. Any ideas? 2011 outback 4 cyl