The quietest room on Earth is a marvel of acoustic engineering built at Orfield Laboratories in Minneapolis, Minnesota. In this anechoic chamber almost all sound is absorbed by three-foot-thick fiberglass wedges so that a person can hear their heart beating, stomach gurgling, and lungs working. The room is designed like one room inside another on special springs to block outside vibrations and many visitors quickly feel disoriented in the absolute silence while engineers use it to test products