What to look for in noise-cancelling headphones

Specs can't tell you everything about headphones, but knowing what to look for helps you narrow the field before you try a pair.

Comfort and fit come first

The best-sounding headphones are useless if you can't wear them for long. Consider:

Over-ear vs. in-ear. Over-ear models usually feel less intrusive over long sessions; earbuds are smaller and better for exercise and travel.
Weight and clamping force for over-ear models.
Ear tip sizes for earbuds — a good seal improves both bass and noise cancellation.

How active noise cancellation works

Active noise cancellation (ANC) uses microphones to pick up outside sound and produces an inverted signal to cancel it out. It's most effective against steady, low-frequency noise such as engines and air conditioning, and less effective against sudden or high-pitched sounds like voices. A good physical seal does a lot of the work too.

Most models also offer a transparency or ambient mode that lets outside sound in when you need to hear your surroundings.

Bluetooth codecs, briefly

A codec determines how audio is compressed over Bluetooth:

SBC — the universal baseline.
AAC — widely supported and works especially well with Apple devices.
aptX variants and LDAC — available mostly on Android phones; can offer higher bitrates when the connection is strong.
LC3 — the codec used by the newer Bluetooth LE Audio standard.

Your phone and headphones must support the same codec to use it.

Features worth checking

Multipoint — connect to two devices at once, such as a laptop and a phone.
Battery life with ANC on — the figure that matters in real use.
Call quality — if you take a lot of calls, read about microphone performance.
Replaceable ear pads and software updates for longevity.