To fight against noise pollution and its effects on our health, DeNoize incubated in Mines Saint-Étienne offers a solution: a “mute” window. Connected, it would be able to analyze the outside sound to adapt to it, and counter it. Its founders, Olivier Schevin and Aman Jindal, were present at CES in Las Vegas from 7 to 10 January to exhibit it.
Double glazing increases thermal insulation, but for the noise it’s another matter. When we are inside, at home or at the office, the vast majority of the noise that reaches us from the exterior goes through the windows. It’s a situation particularly annoying for people living or working near airports or major highways. Reducing this noise pollution, harmful to our health, is a mission that Olivier Schevin and Aman Jindal have taken on since May 2018. This start-up , incubated at Mines Saint-Étienne, offers a solution to improve the soundproofing of windows. “Our challenge now “says Olivier Schevin, co-founder, “is miniaturization of the system to integrate it on the frameworks of Windows”. The concept, which they presented at the CES of LasVegas January 7-10 within the IMT delegation, could integrate easily on standard windows offered today.
The problem of double glazing
“Double glazing is actually less effective in terms of insulation than single glazing, for the same thickness of glass “Said Olivier Schevin. Although it may seem counter intuitive, double glazing offers less resistance to low frequencies – between 50 and 500 Hz. A frequency band that is found to be the main nuisance caused by airports and Main highways. “The double glazing has been designed to meet a thermal insulation problem, but the acoustic aspect was not taken into account ”he specifies.
Double glazing is above all two masses, two panes, with
air or gas between them. This structure is problematic on an acoustic level: the air blocked between the panes allow in resonance, and the noise propagates. To counter this effect, it is now possible to increase the thickness of the windows, or the gap between the two panes. This passive reduction gives a heavy rendering for architecture and is very expensive.
Sound strikes back
The DeNoize innovation is to use sound against itself,
it is an active noise reduction.“We will generate a counter-vibration adapted to the vibration of the noisy exterior in the window” explains Olivier Schevin. “The system produces a vibration opposite to that of the nuisance, creating interference”. Vibrations “cancel out” the noise, reducing up to 75% of the noise transmitted at low frequencies. “This technology is somewhat similar to that of active noise cancelling headphones” adds Olivier Schevin. “The technical difference is the surface of the area you want to treat. For headphones, the area is very small and close to the ear.” The system developed by DeNoize uses sensors to analyze external noise in real time and adapt to it. The actuators produce the counter vibration interfering with the original noise. We must also take into account a unit control, an electronic card in charge of determining the most effective actions of sensors and actuators. Everything is integrated into the window frames. This then implies a nearby electrical connection to provide power to the system. Which is already common in electric roller shutters for example. An innovation that aligns with the evolutions of the smart home .
This exchange between the actuators, sensors and the control unit offers the possibility of a tailor-made reduction in real time, adapted to external variations.“Today we have a functional prototype” specifies Olivier Schevin,“but the system does not calculate in real time yet. To do this, a phase of development is yet to come at an electronics level.”
Olivier Schevin just launched an industrial project with the students of Mines Saint-Étienne to develop a prototype that cancels the noice in real time. They will be focussing on the electronics part of the tech. This because the existing lab electronics are way to big to be integrated into window frames.
“In general, we continue to look for ways to improve the performance at the lowest possible cost.”