Technology

How Active Noise Cancellation Reduces Background Sound

Put on noise-cancelling headphones during a flight or train ride and a steady rumble can become much quieter. Nearby speech, a sudden door slam, or wind around the microphones may still be noticeable. That difference is not simply a matter of how expensive the headphones are. It follows from what active noise cancellation can and cannot do. Active noise cancellation, usually shortened to ANC, uses microphones, electronic processing, and the headphone speakers to reduce some sound reaching your ears. It works alongside the physical blocking provided by ear tips or earcups rather than replacing it.