Voice resonance has more to do with your body/skull structure than anything. One thing that I find interesting is that most phenomenonal singers have rather large mouths. My singing ability actually improved as a child after getting my jaw expanded.
You can kinda test this out yourself. Hold a note with your arms by your side, then again with your hands on top of your head with elbows out. Your voice will have a lot more resonance because you're expanding your chest (this is also the best position to catch your breath in)
Source: classically trained musician taught by PhDs in the various instruments I can play (including singing)
I also have a fun breathing exercise that will make you super light headed, which is fun.
disclaimer: do not attempt if you have any sort of blood pressure or cardiac issues or anything that might be aggrivated by a bit of orothostatic hypotension.
First, inhale for 4 seconds, completely filling your lungs, then exhale, completely emptying your lungs. Repeat, taking one second off the inhale each time, but keeping the exhale at 4 seconds.
The effect is amplified if you bend over while doing it and stand up quickly after.
I don't know if they were referring to the Wim Hof breathing technique, but it will also make you super lightheaded and put you in a meditative state.
Round 1:
about 30 deep breathing breaths. non stop fill it all, empty it all. fast paced
After the last breath, keep your lungs empty and DO NOT BREATH for a whole minute
after the minute, fill your lungs fully then hold for 15 seconds
breath normally for 5 seconds or so
Round 2 (where it gets ''hard'':
same thing, about 30 deep breaths non stop fill it all, empty it all. fast paced again
After the last breath, keep your lungs empty and DO NOT BREATH nor fill them with the slightest bit of air for a whole minute and a half. again, do not fill your lungs at allll.
after the minute and a half you fill it for again 15 seconds
breath normally for 5 seconds or so.
Round 3.
Exact same as round 2. this one will probably where it feels like you wont make it but you got to let the body do it's thing!
Yikes I had no idea about the man, himself. I only really know about the breathing technique and can confirm that it definitely is an interesting experience. It put me in an almost psychedelic state, but it's not something I would want to do regularly.
Thanks for spreading awareness, though. I don't wish to promote bullshit artists. From a quick look into the deaths, it seems they all involved a pool or a body of water and drowning. So hopefully the breathing technique by itself is safe enough, at least.