I'm too lazy to look it up, but I read an article years ago where they took a skull that had been 3d printed off of scans, plugged the holes that would have been blocked by tissue, and blew air through it. They immediately got sounds, so it was definitely shaped as a resonating chamber.

This is true, also general size of chest cavity etc. But they don't know much else. There could be all kinds of obstructive tissue, convoluted airflow pathways, muscular limitations and just about any other barrier you can imagine. It's entirely possible for a big barrel chest and other appropriate anatomy to produce a cute little whistle or some kind of baby dinosaur from a Hollywood movie trill.