Noise-cancelling headphones: how they work and what to buy

Active noise cancelling (ANC) can turn a noisy train carriage into a quiet room. Here's how it works, and how to pick a pair that suits you.

How ANC works

Tiny microphones on the headphones listen to the noise around you, and the headphones play an inverted copy of that sound. The two cancel each other out, especially low, steady sounds like engines and air conditioning.

What to look for

• Battery life: 20 to 40 hours is a good range
• Comfort: lightweight, with soft padding, for long listening
• Transparency mode: lets you hear announcements without removing them
• Codecs and multipoint: connect to your phone and laptop at once

Over-ear or earbuds?

Over-ear headphones usually cancel more noise and sound fuller, while earbuds are smaller and better for exercise. If you commute or work in an open office, go over-ear.