Traverse LS 2015 - 36k
I am having similar issues, but its like an old door opening sound, when pressing/depressing the brake pedal.
This has been happening since I drove from the car dealer 6 weeks ago, and when i turned the radio down, which
the Salesman had turned on, before i entered for the test drive, so i didnt notice, and he probably knew of this problem.
Since then GM advised me to take it to their Service center, and they would then decide if they would assist me with the bill, but only after
i pay for the diagnostics. The cost for diags is $150 upwards, depending on how much work is required. I cant afford the possibility of a few hundreds
so I have to stake it out until then.