"The room of containment, technically an “anechoic chamber,” is the quietest place on the planet — according to some. According to others, it’s more like the second-quietest. It is quieter than any place most people will ever go, unless they make a point of going to multiple anechoic chambers over the course of a lifetime."

https://www.nytimes.com/2022/11/23/magazine/quiet-chamber-minneapolis.html