Look, the "45 minutes" thing is total clickbait. I've been in an anechoic chamber and it is a little disconcerting and weird to suddenly find yourself hearing nothing at all. I only spent a few minutes in there, and it's not uncomfortable at first, but it feels good to get out. It's basically just a feeling of disorientation.
But I have no doubt that, properly motivated, you could easily spend an hour in there. Hell, if I had access to one I'd go do it right now just for dumb internet bragging rights.
I've been in an anechoic chamber ... and it's not uncomfortable at first, but it feels good to get out
Not all anechoic chambers are equal, and not all anechoic chambers are necessarily quiet - they're only as quiet as they need to be for whatever it's designed to test (an anechoic chamber designed to test ICE equipment might have background noise levels in the 40-50 dBA range), so be careful about extrapolating your experience to the quietest anechoic chamber in the world.
But I have no doubt that, properly motivated, you could easily spend an hour in there. Hell, if I had access to one I'd go do it right now just for dumb internet bragging rights.