In-ear, on-ear, over-ear: the difference is the seal

One difference, and it is not sound quality

Shops sort headphones by shape: something that goes in your ear canal, something that rests on your ear, something that surrounds it. That is a description, not a reason to choose one.

The reason is what the shape does to the seal. A sealed earpiece keeps the room out and your music in; an unsealed one lets both travel. Everything you will notice day to day — on a train, in an open-plan office, at your desk at night — comes from that single fact.

One footnote that costs people money: over-ear headphones come in two kinds. Closed ones behave as above. Open ones leak on purpose, because the open back is what gives them their roomy sound — they are made for a quiet room of your own, and they are the wrong buy for a commute, however good the reviews are.

What you actually notice

• On the move. Sealed in-ears punch far above their size, because the seal does the work no electronics can do. This is why a cheap sealed earbud can beat an expensive on-ear on a bus.
• In a shared room. On-ears leak the most of the three. If you take calls next to someone, they hear your call.
• After two hours. Over-ears spread the pressure over the side of your head instead of pressing on the ear itself, so they usually win on long sessions — at the cost of heat.
• If you wear glasses. The arm of your glasses breaks the seal of an over-ear cushion. It is a small gap and it costs a surprising amount of isolation.
• In a bag. In-ears disappear into a pocket; over-ears need the space of a small lunchbox. Nothing else about them changes this.

There is no best shape. There is a best shape for where you will actually use them, which is usually not where you try them.

Noise cancelling is not the same as isolation

This is the single most expensive confusion in the category, and the box encourages it.

Isolation is physical: the material blocks sound. Cancelling is electronic: microphones listen to the noise outside and the headphone plays the opposite of it. They work on different things.

• Cancelling is very good at steady low sounds: an engine, a fan, air conditioning, the rumble of a train.
• It is much weaker on voices and on sharp sudden noises, which is exactly what bothers you in an office or a café.
• It does not replace a seal. On an in-ear, if the tip does not fit your canal, cancelling cannot rescue it — and the wrong tip is the most common reason people think a pair sounds thin.

Before paying for cancelling, ask what you are trying to block. If the answer is colleagues talking, a good seal will do more than an expensive circuit.

The numbers on the box

• Driver size in millimetres. Bigger is not better; it only tells you how much room the designer had. It cannot be compared across shapes at all.
• Frequency response, usually 20 Hz to 20 kHz. Printed on almost every box, including the worst ones. Without a tolerance figure it says nothing.
• Battery life. Measured with cancelling off and at moderate volume, which is not how you will use them. Expect less.
• Codecs and hi-res badges. They matter far less than fit. A perfect codec through a seal that leaks is a worse result than the opposite.

Side by side

And then there is the price

Headphones are the category where the crossed-out price is least trustworthy, because models are replaced constantly and the old list price stays printed long after anyone paid it.

• Ask what the discount is measured against. A percentage off a two-year-old list price is not a saving. A percentage off what the pair actually sold for last month is.
• Use the reference the store itself shows. On Amazon.com that is often a typical price: the median of what customers actually paid over the previous 90 days. It is much harder to inflate, and it is the one we quote when we publish.
• Check the exact model code, not the family name. Manufacturers keep a successful name across revisions that sound different, and the one on offer is often the older revision — which is fine if you are paying older-revision money.
• Watch the condition. Renewed and open-box listings are common here and can be a genuine bargain, but they are not new, and the discount should reflect that and not only the list price.

This is the same check we run before we publish anything. If a price does not survive it, the deal does not go out — which is why some days we publish less.