Active noise control applied to open windows

Active opening windows are newly developed concepts by TechnoFirst to cope with noise disturbances while your window is opened to a noisy environment. Indeed, opening your window reduces the acoustic insulation. That is why TechnoFirst designed an Active Noise Reduction-based solution for windows (ANR). The first one is related to sliding windows: the active window. A loudspeakers line integrated in the window joinery generates a counter-noise, to minimize the noise between 20 and 500 Hz measured by microphones integrated in the window opening. The latter is covered with passive materials coping with higher frequencies. Thus the sound transmission through the window opening is reduced up to 25 dB. The second application enables natural ventilation of a room while minimizing the intrusion of pollution (noise and air) from outside: the active labyrinth. It is composed of ducts including an ANR system and an anti-pollution filter. The electronic processing system is composed of an ultra-compact loudspeaker (designed by the Fraunhofer IBP) and sensors connected to a controller producing the mirror noise which will attenuate low and medium frequencies ([20 - 1700] Hz). The system is thus able to reduce the noise level up to 30 dB compared to a typical window ajar.