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Headphone glossary
Headphone spec sheets speak a language of their own. Here are the forty or so terms you'll run into most often, each defined in two or three sentences, with no background in acoustics assumed.
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- 2.4 GHz dongle
- A small USB adapter 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: Gaming audio: latency, spatial sound and the mic
A
- AAC
- The codec Apple uses for Bluetooth, also used 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 canceling)
- A technique that picks up ambient noise with microphones and emits the inverse wave to cancel it. Very effective against low, steady sounds (engines, ventilation), much less so against voices and brief noises. Related guide: Active noise canceling vs. 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 TV in a public place, announcements. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
B
- Balanced armature
- A miniature driver borrowed from hearing aids and used in in-ear models. Precise in the mids and treble; several are often combined to cover the full spectrum. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
- Bluetooth codec
- The compression scheme used to send sound over Bluetooth: SBC, AAC, aptX, LDAC, LC3. The phone and the headphones must both support the same codec to use it. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
- Bone conduction
- Sound transmitted to the inner ear through vibrations 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 with sealed ear cups. They block outside noise, keep the sound to the wearer and deliver punchy bass, with a narrower soundstage. Related guide: Open-back vs. closed-back headphones: what an open design changes about the sound
D
- DAC
- Digital-to-analog 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: how to listen for hours without harming your ears
- Distortion (THD)
- Alteration of the signal by the driver, which adds sounds that aren't in the recording. Expressed as a percentage, it rises 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 speaker. 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 common technology: a voice coil sitting in the field of a magnet drives a diaphragm. Rugged, 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 earbuds in the ear canal. Their size determines bass, isolation and comfort. Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones should you choose?
- Equalizer (EQ)
- A control that raises or lowers the level of specific frequency bands. It lets you correct a headphone's signature or tailor it to your taste. Related guide: Frequency response and sound signature: how to read a headphone's sound
F
- Frequency response
- A curve showing how loudly a pair of headphones reproduces each frequency, from bass to treble. It is the measurement that best explains a headphone's sonic character. Related guide: Frequency response and sound signature: how to read a headphone's sound
H
- Harman curve
- A target response curve developed by Harman researchers from blind listening tests. It matches the sound most listeners judge to be the most natural and serves as an industry benchmark. Related guide: Frequency response and sound signature: how to read a headphone's sound
- Headphone amplifier
- A device that supplies the voltage and current demanding headphones need. Useful when the source can't deliver enough volume or headroom; otherwise it makes no audible difference. 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 a headphone's sound
I
- Impedance
- A headphone's electrical resistance, in ohms (Ω), ranging from 16 to 600 Ω depending on the model. Together with sensitivity, it determines whether a device can drive it properly. Related guide: Impedance, sensitivity and amplification: do your headphones need an amp?
- In-ear
- An earbud whose soft tip seals the ear canal. Highly isolating and discreet when the tip is the right size; stage models are known as IEMs (in-ear monitors). Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones should you choose?
- IP rating
- A rating of resistance to dust (first digit) and water (second digit). IPX4 withstands splashes and sweat; IPX7 and IP68 can handle immersion.
L
- Latency
- The delay between a device sending out a sound and that sound reaching the headphones, in milliseconds. Negligible over a wire, 150 to 250 ms over classic Bluetooth: a problem in gaming. Related guide: Gaming audio: latency, spatial sound and the mic
- LDAC
- Sony's Bluetooth codec, built into Android, capable of reaching 990 kbps. 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 multiple 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, a computer and a phone for example, 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 sessions; also called supra-aural. Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones should you choose?
- Open-back headphones
- Headphones whose perforated ear cups let air and sound pass in both directions. The sound is natural and spacious, but they don't isolate, and your music leaks out. Related guide: Open-back vs. closed-back headphones: what an open design changes about the sound
- Open-ear
- A family of earbuds that leave the ear canal clear: bone conduction or small speakers positioned 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 should you choose?
- Over-ear
- A headphone design whose ear pads fully surround the ear and rest against the head. The most comfortable over long sessions; also called circumaural. Related guide: Over-ear, on-ear, in-ear or open-ear: which type of headphones should you 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 mids and treble and depends entirely on the seal. Related guide: Active noise canceling vs. passive isolation: what each one really does
- Planar magnetic
- A driver whose diaphragm, a flat film carrying the conductor, is driven across its entire surface between rows of magnets. Deep bass and low distortion, but heavy, expensive headphones. Related guide: Dynamic, planar, balanced armature, electrostatic: headphone drivers explained
S
- SBC
- The baseline Bluetooth codec, mandatory on every audio device. Its quality is decent at full bitrate; it is the fallback when the two devices have no other codec in common. Related guide: Bluetooth codecs and latency: SBC, AAC, aptX, LDAC, LC3
- Sensitivity
- The sound level a pair of headphones produces 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 keeps you from talking too loudly when wearing closed-back headphones. Related guide: Gaming audio: latency, spatial sound and the mic
- Sound signature
- The balance of bass, mids and treble the manufacturer aimed for: neutral, warm, bright or V-shaped. You can read it on the frequency response curve. Related guide: Frequency response and sound signature: how to read a headphone's sound
- Soundstage
- The sense of space a pair of headphones creates: width, depth and the placement of instruments around your head. It is generally wider on open-back headphones. Related guide: Open-back vs. closed-back headphones: what an open design changes about the sound
- Spatial audio (3D audio)
- Processing that places sounds around the listener by simulating the way the head and ears filter sound depending on its direction. It works with any stereo headphones. Related guide: Gaming audio: latency, spatial sound and the mic
T
- Tinnitus
- Ringing or buzzing heard with no outside sound source. It often signals excessive noise exposure; if it lasts more than 24 hours, see a doctor. Related guide: Volume and hearing health: how to listen for hours without harming your ears
- Transparency mode
- A feature of noise-canceling 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 canceling vs. passive isolation: what each one really does
V
- V-shaped signature
- A sound signature with boosted bass and treble and recessed mids. Exciting with modern music, more fatiguing over long sessions. Related guide: Frequency response and sound signature: how to read a headphone's sound
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 canceling vs. passive isolation: what each one really doesHow active noise canceling works, why it erases low rumbles but not voices, and when good passive isolation is all you really need.
- Over-ear, on-ear, in-ear or open-ear: which type of headphones should you choose?Over-ear headphones, on-ear headphones, in-ear earbuds or open-ear: comfort, isolation, sound and best uses for each type, with a comparison table.