The famous Harvard anechoic chamber was later degraded by mechanical noise

Evidence

I am intrigued by the fact that the quietest room in New England has apparently been destroyed in favor of housekeeping equipment emitting a symphony of loud mechanical sounds. — George Michelsen Foy, Zero Decibels, 232

Categorization

• corroborated: 2 independent passages support this claim — George Michelsen Foy, Zero Decibels: The Quest for Absolute…, 232