A team of researchers at Nanyang Technological University in Singapore developed a prototype, called the Anti-Noise Control Window, that expands the concept of noise-cancelling headphones to encompass an entire room. The prototypes consist of 24 small speakers that are placed in a window and emit sound waves that correspond to incoming noise and cancel it out. To capture incoming sounds, the system uses a microphone positioned outside the window to detect sound waves, and a computer controller to determine the wave frequency needed to neutralise the sound. This is then transmitted to the speakers on the window frame. Researcher Dr Bhan Lam, at Nanyang’s Centre for Information Sciences and Systems, explains his interest in the project: “I grew up in Singapore. It’s a small city with a lot of noise, so I have some motivation to solve this problem.” The system is best at moderating the types of steady noise sources found between 300 and 1,000 hertz.