Audio-Technica ATH-M50xBT2

How the headphones sit: over the ear, on the ear, in the ear canal, in the outer ear, beside the ear or on the cheekbone.

Two separate earbuds with no wire between them, charged in a case.

They play over Bluetooth, without a cable to the phone.

The plug for a cable, so you can also listen wired, for instance on a plane or with a battery that has run out.

They play sound over a USB-C cable, straight from a phone or a laptop. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

Whether the ear cups are closed or open at the back. Closed keeps sound in and out, open sounds more spacious but lets everyone around you hear.

The kind of speaker inside. Dynamic drivers are the most common. Planar and electrostatic ones are mostly found in expensive headphones for home listening.

The diameter of the speaker inside. A bigger driver does not by itself mean better sound.

They fold up to take less room in a bag.

What the headphones or one earbud weigh. Lighter is more comfortable for hours at a time.

How you play, pause and change the volume on the headphones themselves.

How many microphones the maker counts, for calls and noise cancelling together.

The lowest tone the maker says they play. It says little about how the bass actually sounds.

The highest tone the maker says they play. Adult hearing stops well below most figures.

The electrical resistance. Wired headphones with a high impedance need an amplifier to play loud enough.

How loud they play on a given signal. A higher figure plays louder from a weak source, such as a phone.

You can adjust bass and treble in the maker’s app.

Sound that seems to come from around you rather than from inside your head. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

How the headphones cancel outside noise with microphones. Hybrid uses microphones outside and inside the cup, adaptive also adjusts to the sound around you. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

Lets outside sound through on purpose, so you hear traffic or a colleague without taking them off. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

Can work as a hearing aid for mild to moderate hearing loss, where the maker has it approved. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

The Bluetooth version. A newer one connects more steadily and uses less power, if the phone has it too.

How the sound is packed for Bluetooth. AAC suits iPhones, aptX and LDAC carry more detail from Android phones that support them.

Connected to two devices at once, such as a phone and a laptop, and switching by itself to the one that plays.

How many devices they stay connected to at once.

The newer Bluetooth standard for sound, with the LC3 codec: better sound on less power, with phones that support it. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

Can listen to a Bluetooth broadcast, such as a TV, an airport announcement or a friend sharing music. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

Pairs in one tap with an Android phone.

Whose phones the headphones are made for. Some features, such as one-tap pairing or spatial audio, work only with that maker’s phones.

How far from the phone the maker says the connection holds, without walls in between.

How long they play on one charge with noise cancelling off.

How many minutes of charging give the playback below.

How many hours of playback a short fast charge gives.

How long a full charge takes.

The case or the headphones charge on a Qi pad, without a cable. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

The plug the headphones or their case charge through.

The music pauses when you take them off and plays on when you put them back. On this model: Assumed, not a stated fact: the maker's full specification does not name it, so we take it as no.

The voice assistants you can call up from the headphones.

The name of the maker’s app.