Scientists explain how they test sound in one of the quietest rooms on earth

You can barely hear anyone talk unless they are facing you directly. The sound is damped, so there is no echo or reverberation in the room. It is literally one of the quietest places you will find.

The walls are especially made for quiet in the room. They are made of fiberglass wedges that absorb the sound, thus no sound is bounced back to you. It’s a room within a room. Literally, the room is not connected to the rest of the building, so no outside noises or vibrations can interfere with measurements. The walls, ceiling and even the floor all absorb sound.

3M originally created the room in 1964 to test the sound of copy machines, to ensure they were as quiet as possible. It’s one of a handful of such sites in the U.S. It is still state-of-the-art when it comes to sound damping, measuring a staggering 10 decibels of sound – incredible when you think a quiet conversation measures 60 decibels and the rustling of leaves 40 decibels. The room is quiet.

3M now uses the room for research related to automotive and aerospace projects. The goal: to test new materials or systems in a room with no echo. “We test for sound in the absence of sound,” says Ronald Gerdes, an acoustics modeling research and development specialist. As cars become lighter and the materials more pliable, it is important to measure the sound of these materials.

“We are quieting automotive parts and residential components,” says Tom. “In essence, screening new materials to silence.”

The need for comfort and the lowest possible noise emissions from cars is continuously increasing. Acoustic factors in vehicles’ interiors are also changing, with new technological trends such as lightweight construction or hybrid and electric cars. NVHT solutions (noise, vibration, harshness, thermal) by 3M offer numerous benefits in sound absorption, damping and thermal insulation. They allow for new design freedom and flexibility of applications.