Explainers
Headphone glossary
Headphone spec sheets speak a language of their own. Here are the forty or so terms you will come across most often, each defined in two or three sentences, with no knowledge of acoustics assumed.
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- 2.4 GHz dongle
- A small USB stick that connects a wireless headset to a computer or console over a proprietary radio link. Its latency, 20 to 30 ms, is imperceptible in games. Related guide: Sound in gaming: latency, spatial audio and the mic
A
- AAC
- The codec used by Apple for Bluetooth and by most streaming services. It is the best codec available on an iPhone. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
- ANC (active noise cancelling)
- A technique that picks up ambient noise with microphones and emits the inverse wave to cancel it. Very effective against low, continuous sounds (engines, ventilation), much less so against voices and brief noises. Related guide: Active noise cancelling or passive isolation: what each one really does
- aptX
- Qualcomm's family of Bluetooth codecs, found on many Android phones: aptX, aptX HD, aptX Adaptive (low latency) and aptX Lossless (CD quality). Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
- Auracast
- A Bluetooth LE Audio feature that broadcasts a single audio stream to an unlimited number of headphones: sharing music, the television in a public place, announcements. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
B
- Balanced armature
- A miniature driver derived from hearing aids and used in in-ear earphones. Precise in the mids and treble; several are often combined to cover the whole spectrum. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
- Bluetooth codec
- The compression method used to send sound over Bluetooth: SBC, AAC, aptX, LDAC, LC3. The phone and the headphones must both support the same codec in order to use it. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
- Bone conduction
- Transmission of sound to the inner ear through vibration of the skull bones, bypassing the eardrum. Headphones that use it rest on the cheekbones and leave the ear open. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
C
- Closed-back headphones
- Headphones whose earcups are sealed. They block outside noise, keep the sound to the wearer and deliver punchy bass, with a narrower soundstage. Related guide: Open-back or closed-back headphones: what openness changes in the sound
D
- DAC
- Digital-to-analogue converter: it turns digital audio data into an electrical signal. Every phone, computer and pair of wireless headphones contains one. Related guide: Impedance, sensitivity and amplification: do your headphones need an amp?
- Decibel (dB)
- A logarithmic unit of sound level. A 3 dB increase doubles the sound energy; a 10 dB increase is perceived as twice as loud. Related guide: Volume and hearing health: listening at length without damaging your ears
- Distortion (THD)
- Deformation of the signal by the driver, which adds sounds that are not in the recording. Expressed as a percentage, it increases at high volume, especially in the bass. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
- Driver (transducer)
- The component that turns the electrical signal into sound: the headphone's loudspeaker. The main technologies are dynamic, planar magnetic, balanced armature and electrostatic. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
- Dynamic driver
- The most widespread technology: a moving coil, sitting in the field of a magnet, drives a diaphragm. Robust, inexpensive and generous in the bass. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
E
- Ear tips
- Soft silicone or foam pieces that seal in-ear earphones in the ear canal. Their size determines the bass, the isolation and the comfort. Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones to choose
- Equaliser (EQ)
- A control that raises or lowers the level of particular frequency bands. It lets you correct the signature of a pair of headphones or tailor it to your taste. Related guide: Frequency response and sound signature: how to read the sound of a pair of headphones
F
- Frequency response
- A curve showing the level at which headphones reproduce each frequency, from bass to treble. It is the measurement that best explains the sonic character of a pair of headphones. Related guide: Frequency response and sound signature: how to read the sound of a pair of headphones
H
- Harman curve
- A target response curve established by Harman's researchers from blind listening tests. It corresponds to the sound that a majority of listeners judge the most natural, and serves as an industry reference. Related guide: Frequency response and sound signature: how to read the sound of a pair of headphones
- Headphone amplifier
- A device that supplies the voltage and current that demanding headphones need. Useful when the source cannot deliver enough volume or headroom; otherwise it has no audible effect. Related guide: Impedance, sensitivity and amplification: do your headphones need an amp?
- Hertz (Hz)
- The unit of frequency: the number of vibrations per second. At best, the human ear hears from 20 Hz (the deepest bass) to 20,000 Hz (the highest treble). Related guide: Frequency response and sound signature: how to read the sound of a pair of headphones
I
- Impedance
- The electrical resistance of a pair of headphones, in ohms (Ω), from 16 to 600 Ω depending on the model. Together with sensitivity, it determines whether a device can drive them properly. Related guide: Impedance, sensitivity and amplification: do your headphones need an amp?
- In-ear
- An earphone whose soft tip seals the ear canal. Highly isolating and discreet when it is the right size; stage models are also known as IEMs (in-ear monitors). Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones to choose
- IP rating
- A classification of resistance to dust (first digit) and water (second digit). IPX4 withstands splashes and sweat; IPX7 and IP68 withstand immersion.
L
- Latency
- The delay between a device producing a sound and that sound arriving in the headphones, in milliseconds. Negligible when wired, 150 to 250 ms over classic Bluetooth: a nuisance in gaming. Related guide: Sound in gaming: latency, spatial audio and the mic
- LDAC
- Sony's Bluetooth codec, built into Android and capable of reaching 990 kbit/s. It lowers its bitrate automatically when the radio link deteriorates. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
- LE Audio and LC3
- The new generation of Bluetooth audio, built on the low-energy variant and the LC3 codec: better quality at the same bitrate, a good-quality mic while you listen, and broadcasting to several headphones. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
M
- Multipoint
- The ability of Bluetooth headphones to stay connected to two devices at once, for example a computer and a phone, and to switch from one to the other automatically. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
O
- On-ear
- A headphone design whose ear pads rest on the outer ear. More compact than an over-ear model, but less isolating and less comfortable over long periods; also called supra-aural. Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones to choose
- Open-back headphones
- Headphones whose perforated earcups let air and sound pass in both directions. The sound is natural and spacious, but they offer no isolation and leak your music. Related guide: Open-back or closed-back headphones: what openness changes in the sound
- Open-ear
- A family of earphones that leave the ear canal clear: bone conduction, or small speakers placed in front of the ear. You hear everything around you, at the cost of weak bass. Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones to choose
- Over-ear
- A headphone design whose ear pads completely surround the ear and rest on the skull. The most comfortable over long periods; also called circumaural. Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones to choose
P
- Passive isolation
- Noise reduction achieved solely by the physical barrier of the ear pads or ear tips, with no electronics. It works mainly on the mids and treble and depends entirely on the seal. Related guide: Active noise cancelling or passive isolation: what each one really does
- Planar magnetic
- A driver whose diaphragm, a flat film carrying the conductor, is driven across its whole surface between rows of magnets. Deep bass and low distortion, but heavy, costly headphones. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
S
- SBC
- The basic Bluetooth codec, mandatory on every audio device. Its quality is decent at full bitrate; it is the fallback codec when the two devices have no other in common. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
- Sensitivity
- The sound level headphones produce for a given amount of energy, in dB/mW or dB/V. The higher it is, the less power the headphones need. Related guide: Impedance, sensitivity and amplification: do your headphones need an amp?
- Sidetone (mic monitoring)
- A feature that feeds your own voice back into the headset during a call or a game. It stops you talking too loudly when wearing closed-back headphones. Related guide: Sound in gaming: latency, spatial audio and the mic
- Sound signature
- The balance between bass, mids and treble chosen by the manufacturer: neutral, warm, bright or V-shaped. It can be read from the frequency response curve. Related guide: Frequency response and sound signature: how to read the sound of a pair of headphones
- Soundstage
- The sense of space a pair of headphones conveys: width, depth and the placement of instruments around your head. It is generally more expansive on open-back headphones. Related guide: Open-back or closed-back headphones: what openness changes in the sound
- Spatial audio (3D sound)
- Processing that places sounds around the listener by simulating the way the head and ears filter sound according to its direction. It works with any stereo headphones. Related guide: Sound in gaming: latency, spatial audio and the mic
T
- Tinnitus
- Ringing or buzzing heard with no external sound source. It often signals excessive exposure to noise; if it lasts more than 24 hours, see a doctor. Related guide: Volume and hearing health: listening at length without damaging your ears
- Transparency mode
- A feature of noise-cancelling headphones that feeds in the outside sound picked up by the mics, so you can hear an announcement or a conversation without taking them off. Related guide: Active noise cancelling or passive isolation: what each one really does
V
- V-shaped signature
- A sound signature with boosted bass and treble and recessed mids. Spectacular with modern music, more tiring over long sessions. Related guide: Frequency response and sound signature: how to read the sound of a pair of headphones
Understand before you buy
- How to choose headphones: the complete methodUse, ambient noise, form factor, connection, sound signature, isolation, priorities, budget: a step-by-step method for choosing headphones or earbuds.
- Active noise cancelling or passive isolation: what each one really doesHow active noise cancelling works, why it wipes out low rumble but not voices, and when good passive isolation is all you need.
- Over-ear, on-ear, in-ear or open-ear: which type of headphones to chooseOver-ear headphones, on-ear headphones, in-ear or open-ear earbuds: the comfort, isolation, sound and uses of each type, with a comparison table.