One of the quietest rooms in the country, also known as the Dead Room, is located at the Faculty of Applied Sciences. The echo-free room was designed to absorb as much sound as possible, primarily for acoustic measurement purposes and other experiments involving direct sound.
"It was built at the beginning of the 60s, just before the Applied Sciences building. They built the anechoic room first, and later the faculty building around it," said Henry den Bok, room administrator. The fact that it‘s completely isolated from the rest of the building, and built on a special foundation of pillars with rubber, prevents incoming sounds and vibrations. The walls, ceiling and floor inside are covered in wedges made from an absorbent material that prevents reflections of sound. "When it was first built, they used foam rubber. In the mid-80s it was renovated, and they're now made from glass wool, just like the insulation used in houses," he said. "The glass wool wedges are a metre long, and behind them is 40 cm of concrete, leaving 8 m x 8 m x 8 m inside." There’s a specially constructed ventilation system, and a hermetically closing door.
It is often said that the room is so quiet you can hear your own heart beating and your blood flow, and a feeling of pressure in the ears is often reported too. Although not used much for experiments these days, the room still attracts plenty of visitors. If you want to experience the deathly silence of the dead room yourself, it's currently accessible via the Backstage Tours run by Science Centre Delft.