Noise cancelling device by NTU EEE scientists halves noise pollution through open windows

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Singapore – Researchers from the School of Electrical and Electronic Engineering (NTU EEE) at Nanyang Technological University, Singapore have developed a device that can reduce noise pollution entering buildings through open windows.

Designed to be mounted onto window grilles, the device can reduce up to 50 per cent of noise coming from nearby environments such as busy roads, train tracks or from construction activities; and uses ‘active noise control’ technology – found in many high-end headphones that cancels external noise – and adapted to work in a large open area.

The benefits are two-fold: windows can be left open for fresh air without disturbance from external noise pollution and reduces the need for air-conditioning to keep the interiors of buildings and homes cool.

NTU EEE Professor Gan Woon Seng, Director for NTU EEE’s Centre for Infocomm Technology (INFINITUS) who led the research said, “In comparison to noise cancellation headphones, what we have achieved is far more technically challenging as we need to control the noise in a large open area instead of just around the ear.”

Currently at the prototype stage, the device uses 8 watts of power, similar to a small portable Bluetooth speaker. Several units are placed together to form a grid-like array on a window grille to reduce external noise. The device uses a special sound emitting mechanism which works like a speaker and is hooked up to a processing unit. Equipped with a microphone, it can detect noise even before it reaches the window and computes the attributes of the incoming noise in real-time.

It quickly emits a countering sound or “anti-noise” that has the same waveform characteristics of the invading noise but with one difference: it is inverted or “flipped”. When both outside noise and anti-noise converge, they cancel each other out, resulting in a softer ambient sound entering living spaces.

“Our innovation not only computes the right amount and type of “anti-noise” to emit; but also, does it faster than the detected noise can reach within a building,” explained Prof Gan.

The NTU EEE research team is now developing the technology further by improving its noise cancellation efficiency, making them smaller, and more cost-effective to produce. The researchers are also working with government agencies in Singapore to further enhance the technology to make it viable for commercial and residential applications.

The project is jointly developed with the University of Southampton in the United Kingdom, and Tottori University in Japan. It is supported by Singapore’s Ministry of National Development and the National Research Foundation in the Prime Minister’s Office, under the ‘Land and Liveability National Innovation Challenge’ (L2 NIC) Research Programme.

This initiative seeks to leverage R&D to develop innovative technological solutions to increase Singapore’s land capacity for its long-term development needs and provide tech-based options for future generations.