My 2007 XC90 (3.2, AWD, ~144K miles, owned it for only ~1 year) needs new brakes all around, and I'm hoping that this wise community can give me some advice. Being a graduate student, I need to keep the budget a priority, but I don't want to take chances with my or my family's safety for something ...

It is difficult to determine just what I am hearing in the audio/video, but it sounds like the droning (loud, then softer, then louder again) of a beat frequency. Happens when at least two frequencies are very similar to each other, but not exactly the same. The beat frequency is the difference ...