HOW DOES ACTIVE NOISE CONTROL SOUND-CANCELLING TECHNOLOGY WORK?

Active noise control is found in high-end noise cancelling headphones and promises to reduce the amount of ambient sound entering a wearer's ears. Some systems claim to be capable of reducing noise by up to 90 per cent, although this may be as low as 50 per cent in some models. The technology has existed for several decades, but has relatively recently been used in commercial headphones. Full size speakers equipped with the technology is used to cancel out the disruptive noises of transformers, compressors and other low frequency machinery.