Maybe its a breathing technique? I would be interested to know how each man in the video above breaths at night, nose breather or mouth breather. I have always sounded nasally, I constantly feel a stuffy nose and suffer seasonal sinus infections.
I just wonder if the air passing through the voice box has anything to do with blockages in the nasal passages. I don't have sleep apnea nor do I snore at night. I have noticed, when phlegm has got caught in my throat, before I eject it, my voice changes suddenly, in a momentary "stuck" position until I clear my throat.
Do you sleep with your mouth open or closed?
If closed: Is your voice deeper like drum?
If open: Is your voice higher or nasal?