Dual noise sensor technology, featuring two microphones on each earcup, captures ambient noise and passes the data to the HD Noise Cancelling Processor QN1. Using a new algorithm, the HD Noise Cancelling Processor QN1 then applies noise-cancelling processing in real time to a range of acoustic environments.To maximise noise-cancelling performance, the WH-1000XM4 headphones incorporate two technologies: Personal Noise-Cancelling Optimiser, designed specifically for you, and Atmospheric-Pressure Optimising, designed specifically for air travel.Adjust ambient sound with the Sony | Headphones Connect app to cancel noise while still allowing essential sounds, like transport announcements, through when you're listening on the move.A built-in analogue amplifier integrated in the HD Noise Cancelling Processor QN1 realises an unmatched signal-to-noise ratio for low distortion and exceptional sound quality for portable devices.Powerful 40-mm drivers with Liquid Crystal Polymer (LCP) diaphragms make the headphones perfect for handling heavy beats and can reproduce a full range of frequencies up to 40 kHz.