According to the United Nations Environment Programme, long-term exposure to noise pollution can adversely affect human health. With our cities getting louder, it's more important than ever to muffle this unseen hazard. In Singapore, Gan Woon-Seng, Professor of Audio Engineering at NTU, is focused on developing technology that can mitigate urban noise. Gan has developed a device that can be mounted on windows and emit soundwaves to cancel out offending noise from outside. He and his team are also working on another noise-reduction technology using a technique called 'intentional masking', where a positive natural sound is played to divert attention away from negative noise.