I'll say this enough and eventually may not have to repeat it. For now, the broken record still plays....
Last work done--changed pads?
What else did you do?
What else did you not do that you should have?
We don't have enough info, but.....
I'm going to suggest that you need to check the bushings (yes, they do exist) in the front calipers. Their job is to allow free movement of the calipers (ie. float) while providing noise isolation by avoiding metal-to-metal contact between the caliper slide pins/sleeves.
If all you did was replace the pads, there is a chance the bushings are in need of replacement as well, and under certain conditions there is the presence of noise from the caliper housing's contact on the sleeve(s).
GM caliper service kit 18005606--enough parts and lube for both front calipers.