Blocking the transmission of bass frequencies in noisy environments with Sound Relief a thin, light-weight and modular soundproof wall.
Sound Relief is an active soundproofing concept that acts as a noise-breaker between a closed and open space. It is composed of loudspeakers electronically controlled to reduce the energy emanating from a noise source. Whereas other solutions require additional microphones to subtract noise, the loudspeakers used for Sound Relief simultaneously measure noise and absorb it. Therefore simple electronics can be used to create robust solutions. With Sound Relief quiet zones can exist in noisy environments.
Sound Relief is designed for filtering low frequencies, the most difficult noise to block. Combined with well-known passive material, large spectrum attenuation is obtained. The advantage of this technology is in its simple construction and effective thickness-to-efficiency ratio. The technology is currently at the prototyping stage but can be industrialized for specific applications. Sound Relief could be used to separate the interior of the future Montreux Jazz Café at EPFL.
Alternative types of surfaces (other than loudspeakers) could be used to accomplish the same task, these surfaces being flexible enough to detect a vibration (the noise) and emit a correction. This technology could be easily applied to architectural projects where a variety of materials could be used to absorb and/or control sound in a given area, room and public space.
In 2012, the first Sound Relief prototype was built by researchers at LEMA. This prototype demonstrates the separation of two areas :
- A nightclub enclosure with a loudspeaker diffusing 100 dB sound.
- A lounge area (in front of the loudspeaker barrier) where noise pollution from the nightclub (especially bass) would be expected.
For the prototype, the wall created to divide the nightclub and lounge zone was less than 10 cm in thickness and made up of active loudspeakers that act as filters. Combined with traditional passive material for medium/high frequency filtering, Sound Relief is opaque to sound.
The Sound Relief prototype was tested by more than 1’000 people and all of them, including architects, were very impressed with the performance of the filtering. Future applications are foreseen in cars, aircrafts and boats.
LEMA (Laboratory of Electromagnetism and Acoustics)