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.
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.