Active’s innovative window concept

Context

Heavy traffic, nearby shops, vacuum cleaners and the neighbour’s TV set are all part of our daily soundscape at home and at the workplace. Noise levels are getting higher as the urban fabric becomes ever denser with more and more people per square metre. To protect their indoor comfort, 92% of people instinctively close their windows. This need for soundproofing is also a major challenge for 80%** of architects who erect or renovate buildings. To deliver tailored solutions to professionals and homeowners alike, TECHNAL’s R&D department has been working for the past 3 years on groundbreaking projects to optimise the acoustic properties of door and windows.

Concept

This innovative sliding window* concept provides airborne noise insulation. This innovative sliding window* concept delivers airborne noise insulation even when doors or windows are open. A huge advantage for occupants who want to ventilate a room while protecting themselves against outside noise. Its patented system, developed in partnership with GAMBA ACOUSTIQUE and the CNRS Mechanics and Acoustics Lab, harnesses the combined power of two technologies, one “passive”, the other “active”.

Because they are complementary, they deal with the entire noise frequency spectrum from 500 to 4,000 Hz for the passive technology and 80 to 500 Hz for the active technology. For a window open 10 cm featuring 44.2/14/10 acoustic glazing, sound dampening can achieve 25 dB, i.e. an average of 300 times less noise indoors. As a comparison, this window delivers acoustic dampening of 10 dB when open 10 cm without “passive/active” treatment and 35 dB dampening in closed position.

Passive technology

The concept has been developed and tested on a leaf opening of 10 cm. To absorb noise, this “slit” is edged with two side walls creating a tunnel that acts as a silencer. These side walls are made of an acoustic insulator (mineral wool 6 to 20 cm thick with a depth of about 25 cm) located on the outer uprights of the leaf and the frame upright. When sound travels through this silencer, it is absorbed by the walls across its entire length of its trajectory. The result is a dampened noise in the medium and high frequencies (corresponding to high-pitched sounds like the human voice) entering the room.

Active technology

Noise is a waveform made of “troughs” and “peaks”. The active technology principle consists in analysing this noise in real-time and generating a counter-wave. The reverse wave cancels out these “troughs” and “peaks” in the noise wave. The result is a flattened waveform synonymous of noise reduction, and even cancellation.

To treat the entire height of the slit, eight microphones are located on the inner frame and seven loud speakers are built into the acoustic insulation on the exterior frame. The microphones record incoming noise passing though the tunnel. A computer then analyses it and produces a counter-noise played back through the speakers. This system permanently tests incoming sound and automatically cancels out the low frequency components (deep noises like traffic hum).