What is the buzz/hum in my stock exhaust? on 2002 Chevrolet Suburban 2500

My 02 Suburban has a buzz/hum when i take off from a stop and @2500-3000 rpm. It has 111000 miles on it. A buddy if my said it may be the cats but it sounds metal-on-metal.

So any advice would help, thanks.

2 answers
Heat shield or hanger may have worked its way loose. If you can pound on the exhaust and get it to rattle inside then you have to replace a couple of items...
Exhaust shield loose maybe? Tap along exhaust pipe front to back with a rubber hammer, listen for noise.