• Active noise cancellation involves creation of an antiphase soundwave
• This signal counteracts and ‘cancels out’ the external noise you hear
• It is created using mics on (and in) your headphones alongside a software algorithm
Noise-cancelling headphones use both analog and electronic methods to block out the environmental sound around you, allowing you to listen to your music in peace without distraction.
Active noise cancellation technology was originally implemented in a product (a headset for pilots) by Bose over 30 years ago, and the company has remained synonymous with it since. We asked John Rule, Senior Engineer at Bose Corporation, to explain noise cancellation.
“Today, noise cancellation in the majority of headphones and earbuds is achieved through a combination of both active and passive technologies. For active noise reduction, sophisticated electronics work with microphones both inside and outside the ear cups to sense the sound around you and then measure, compare, and react – instant by instant – to produce an opposing cancellation signal,” says Rule.
Because noise is just a signal, it’s possible for ANC headphones to analyze the unwanted sound around you, and create an opposite version of that signal, which is then added into the music using clever processing. If done well, this will cancel out those unwanted extra sounds, but leave your music sounding just like you expect it to.
Bose’s John Rule emphasizes that it’s not just the circuitry doing the work, though. He says, “Passive noise reduction also plays a role in headphone performance. When you place an earcup over your ear or an earbud in your ear, some noise is physically blocked. The cup or bud design, materials used, clamping force of the headband, shape of the ear tips, and many other factors contribute to a comfortable fit while providing a good seal against incoming noise. When active and passive elements are combined, the result is cancellation of the noise you don’t want to hear, such as a plane engine or annoying vacuum. This lets you hear what you want, whether that’s your music or silence.”


