Buying headphones used to be a simple purchase. There wasn't much to consider in the era of cassette tapes and compact discs. Alas, that simplicity began to fade away in the early 2000s and now it's gone. Headphones are complex. Any product description is certain to include jargon, unexplained acronyms and jazzed-up names for proprietary technology. It’s hard to keep up.

The definitions below are meant to serve as a reference guide, not a buying guide:

Audio

• Amplified headphones usually aren't as special as their marketing suggests: All active noise-cancelling headphones have a built-in amplifier. However, some high-end passive headphones are amplified.

• Binaural calls is another way of saying that a headset is stereo capable.

• Headphones with equalization, or EQ, allow the wearer to emphasize, minimize or balance parts of the audio spectrum. (E.g. Boost vocals or lower the bass.) Some headphones have preset equalization settings while others allow full control of the audible frequency range, usually via a smartphone app.

• Many headphones have a frequency response of 20Hz to 20,000Hz, which is the audible range of human hearing. These numbers offer little clue to how a headphone will actually sound. Frequency response is best measured with respect to sensitivity (+/- X dB). The closer to 0dB, the better.

• Hi-Res Audio (HRA) is any audio format that exceeds the 16-bit/44.1kHz standard found on compact discs. HRA cannot be reproduced over a Bluetooth connection, regardless of a headphones' quality.

• The only true lossless audio file is the original studio master recording. However, uncompressed audio that is recorded and played back at 24 bit/96 kHz or higher is often referred to as "lossless." High quality headphones are capable of replaying lossless audio over a wired connection.

• Headphones and earbuds with low impedance (denoted in Ωs) require minimal power to play at loud volumes. As a result, low impedance headphones are susceptible to blow outs. On the other hand, headphones with high impedance require stronger amplification, but are less likely to be overloaded.

• Sensitivity, denoted in dB, indicates how effectively a headphones' drivers can turn power into sound. Headphones with 100dB of sensitivity will sound approximately twice as loud as those with 90dB of sensitivity, all else being equal. (Perceived “loudness” doubles with every 10dB increase in sensitivity.)

• Sound pressure level (SPL), denoted in dB, indicates how loudly a headphone will play. Many headphones are capable of delivering sound pressure levels above 85dB, which can cause hearing loss.

• Spatialization and localization are the abilities of a headphone to create a virtual space within the listener's mind, then, to pinpoint sounds within that space. For example, being able to hear footsteps approach from behind in a video game or being able to hear the distinct location of each instrument in a musical recording. These effects can be achieved through traditional stereo imaging or via software.

• Tuned drivers is another way of saying that an audio engineer has tweaked the acoustics of the headphones. Any legitimate pair of headphones will have tuned drivers. This is a marketing term that is used to emphasize the organization or the specific engineer who was responsible for the tuning. (E.g. Tuned by Meridian Audio.)

Battery

• mAh is shorthand for milliampere hour and is used to denote the capacity of the batteries found in headphones and charging cases. For reference, a AA battery has around 2,500 mAh.

• Playtime is the battery life of a wireless headphone that is in continuous use.

• When a pair of headphones and its power adapter are both Qualcomm Quick Charge compatible, it allows the headphones to charge rapidly over USB without overheating.

• Headphones and earbuds that support Qi charging can be wirelessly charged using a Qi-certified charger, or, may contain a wireless charging case that uses the Qi (pronounced CHEE) standard.

• Many battery-powered headphones include a USB Type A/B to Micro USB charging cable.

Hardware

• Headphones with 24-bit audio signal processing have a built-in digital to analog converter (DAC) that is capable of transmitting audio at a higher quality than a compact disc (over a wired connection).

• An AMS 3415 chip allows active stereo noise reduction of 20dB or more.

• AUX is shorthand for auxilliary, which means a 3.5mm TRS unbalanced stereo headphone jack.

• BassTurbo is a design feature found in Anker Soundcore earbuds. By adding a tubular gap behind the earbud's driver, bass frequencies are emphasized via physics (i.e. without the aid of software).

• Some headphones have braided cables that are designed to minimize tangles, improve durability or retain shape. Braiding can also decrease interference or resistance, but the impact usually isn't audible.

• The driver size of a headphone (or earbud) is the diameter of its diaphragm, denoted in millimeters. A larger driver is capable of moving more air, but it doesn't necessarily sound better than a smaller driver.

• Dynamic drivers, or neodymium drivers, use a high-powered magnet to move a diaphragm, resulting in sound waves. Many headphones use dynamic drivers because of their low cost and power requirements.

• Ear tips are interchangeable cushions that allow earphones to fit within the ear canal as desired. Many ear tips are made from silicone (more durable) or memory foam (better at isolating outside sounds).

• An FPC antenna, or flexible printer circuit antenna, is small enough to be mounted on a circuit board.

• The H1 chip is an Apple-designed processor that is made specifically for headphones. 

• Sony's HD Noise Canceling Processor QN1e supports hybrid active noise cancellation within earbuds.

• Some headphones include a jack adapter that converts the 3.5mm plug into a 1/4" stereo phone jack.

• An LDS antenna is made with a laser direct structuring process, which allows the antenna to be wrapped internally on a plastic housing (i.e. "we hid the antenna inside the headphones").

• A Litz wire is a type of braided cable that reduces electrical resistance. This type of cable braiding has practical applications (in Qi wireless chargers, for example), but it is unlikely to impact audio quality.

• Microsoft adapter is shorthand for the Xbox One Stereo Headset Adapter, which allows most wired stereo gaming headsets to work with the Xbox One. Some headphones include a generic adapter.

• QCC3003 is the model number of an entry-level system-on-chip (SOC) made by Qualcomm. It supports features like cVC 8.0 and Bluetooth 5.0 and is often found in low-cost Bluetooth headsets.

• QCC3024 is the model number of an entry-level system-on-chip (SOC) made by Qualcomm. It supports voice assistant touch controls and is found in low-cost "smart headphones." 

• QCC5124 is the model number of a versatile system-on-chip (SOC) made by Qualcomm. It supports 192kHz 24-bit audio, digital assistant usage, aptX HD and all forms of active noise cancellation.

• Gaming headsets that contain RGB LED lighting are capable of reproducing more than 16 million hues.

• A stable CSR chip may refer to a low-cost Bluetooth radio that was manufactured by Cambridge Silicon Radio prior to the company's acquisition by Qualcomm in August 2015. However, Qualcomm continues to use the initials “CSR” on some wireless audio systems-on-chips (SoCs). E.g. CSR101x Series.

• A transmitter is another name for the Bluetooth radio found within headphones, earbuds and headsets.

• A TRS audio cable is a stereo headphone cable, however many non-headphone TRS cables are in fact monaural. The acronym “TRS” merely describes the design features of the cable: tip, ring and sleeve.

• Some wired headphones connect via a USB-C plug. This type of connection is compatible with certain smartphones and laptops that no longer support a 3.5mm stereo jack.

Materials

• ABS, or acrylonitrile butadiene styrene, is a versatile, durable and recyclable type of plastic.

• Graphene drivers are speaker diaphragms that are made from a hexagonal pattern of carbon atoms. Graphene is lightweight, strong and highly conductive. It's also expensive. Some manufacturers might be stretching the truth when they claim to use graphene drivers, especially in cheap headphones.

• Leatherette is a type of vinyl or plastic that simulates the look of leather.

• "Memory protein earmuffs" is a poorly-worded translation of polyurethane foam enclosed in protein-infused synthetic leather, or headphone ear cups made from memory foam and leatherette.

• OFC stands for oxygen-free copper, which is sometimes written as OFHC, or oxygen-free high thermal conductivity copper. It is 99.95% pure, whereas most copper is 99.9% pure. This distinction doesn't mean much in terms of audio quality (but, copper purity does matter in certain industrial applications).

• Protein leather is synthetic leather that contains egg-derived protein. It is also called leatherette.

• Thermoplastic polyurethane (TPE) is a durable and versatile plastic that is used headbands.

Microphones

• A cardioid microphone emphasizes sounds that are in front of the microphone.

• A detachable microphone can be completely removed from a headset, usually via a 3.5mm plug.

• A MEMS microphone is a miniature-sized microphone that is capable of delivering high performance. This type of micro electrical mechanical system is contained within a circuit board.

• A retractable microphone flips away from the wearer’s mouth and on some headsets, it may automatically engage the mute button. Retractable mics are prone to failure because the up-and-down motion can cause the headset’s internal cabling to fray or separate.

• Sidetone is a type of audio feedback that is produced by a person's own voice and replayed through a headset. Headsets with variable mic monitoring allow a speaker to control how much sidetone they hear, including the option to hear oneself at the same volume that others do (e.g. in team chat).

• A microphone's signal to noise ratio (denoted in dB) indicates that difference between "good" sound versus the self noise that the microphone creates. The higher the ratio, the better the recording.

Noise Cancellation

• Active noise cancelling (ANC) headphones use microphones to record ambient sounds, then replay those sounds out-of-phase so that the noise cancels itself out. This feature requires a power source.

• Digital noise cancellation doesn’t have a formal definition; therefore, the term is used to describe different things. Digital noise cancellation might be a type of software that is found in active noise cancelling headphones and used to isolate or emphasize what the listener hears. On the other hand, this term is also used to describe the digital noise reduction codecs found in MEMS microphones.

• Feedback active noise cancellation is a type of active noise cancellation where the microphone is placed inside the earcup. This implementation is less effective at preserving musical detail.

• Feedforward active noise cancellation is a type of active noise cancellation where the microphone is placed outside of the earcup. This implementation is less effective at reducing wind noise.

• Hybrid noise cancellation is a best-of-both-worlds approach to active noise cancellation. It utilizes a feedback design and a feedforward design simultaneously (i.e. microphones are inside and outside).

• Passive noise cancellation (PNC), sometimes referred to as noise isolation, is an acoustically-sealed design that functions similarly to earmuffs (in headphones) or earplugs (in earbuds).

Software

• 4D surround is the latest way of saying 3D audio effect, virtual surround sound, spatialized audio or positional audio. Some headphones are more effective than others at virtualizing the location of sounds.

• 7.1 surround sound is a form of digital signal processing that attempts to recreate a home theater listening experience (seven speakers and a subwoofer) within certain headphones and gaming headsets. However, third-party tests have demonstrated that most listeners cannot tell a difference.

• A2DP/AVRCP/HFP/HSP are four basic Bluetooth profiles that allow wireless headsets to function.

• AAC, or advanced audio coding, is a lossy audio compression format that delivers MP3-like audio quality over a Bluetooth connection, however, it is prone to latency and inconsistent performance.

• AI-powered is a fancier way of saying self-calibrating or self-adjusting. Some noise-cancelling headphones use proprietary software to predict noises (or noisy scenarios) and respond in kind.

• aptX is a suite of audio compression algorithms that are owned by Qualcomm and used in Bluetooth headphones, earbuds and headsets. Some notable aptX software found in headphones includes:

  • aptX HD, or high definition, is an audio codec that provides CD-like sound over Bluetooth.

  • aptX LL, or low latency, maintains audio/video synchronization over a Bluetooth connection. 

• BassUp is a type of digital signal processing that intensifies bass frequencies that are played in certain Anker Soundcore headphones. This feature can be turned on and off.

• Custom EQ3 Sound is a feature found in certain JLab headphones and earbuds. These three preset equalizer settings (Signature, Balanced and Bass Boost) can be changed without an app.

• cVc or "clear voice capture" is a Qualcomm voice-boosting technology that is designed to improve phone calls. cVc technology is regularly updated and released under a new version number.

• DSEE Extreme with Edge-AI is a Sony digital signal processing technology that attempts to recreate audio details that have been lost during compression.

• Dolby Atmos for headphones is a Microsoft-supported program that attempts to simulate a 360 degree sound field, which in theory, allows the listener to hear sound effects that move up and down.

• DualEQ is a bass-boosting "workout mode" that's found in some Anker Soundcore sport earbuds. 

• ExtraBass is a battery-powered signal booster that increases low frequencies in Sony ExtraBass headphones. This feature can be turned on and off.

• FastStream (FST) is a low-latency codec that reduces lip-sync issues between a video signal and a Bluetooth audio signal. It was created by Cambridge Silicon Radio (now part of Qualcomm).

• Firmware is permanent software that tells hardware how to operate. Some headphones support downloadable firmware updates, which can unlock new features, fix bugs, or introduce new bugs.

• FLAC, or Free Lossless Audio Codec, is an audio coding format designed by the Xiph.Org Foundation. It is used to deliver lossless compression of digital audio while reducing the storage size of audio files by at least 40%. Headphones cannot replay lossless audio over Bluetooth, regardless of their quality.

• HearID is a feature found in certain Anker Soundcore headphones and earbuds. A listener responds to auditory test tones, then software creates personalized sound settings in response to this feedback.

• Sony's LDAC audio coding technology is designed to allow 24-bit/96kHz audio files (i.e. hi-res audio) to be broadcast over a Bluetooth connection, however, third-party testing disputes this claim.

• RCV, or real clear voice, is an ambient noise-reduction technology developed by Realtek. It is used to minimize wind noise during phone calls and to isolate and enhance the speaker's voice.

• Realtek is a semiconductor company that makes audio drivers like Realtek HD Audio Manager. This software allows a PC to recognize a pair of headphones, and subsequently, it allows a user to make audio adjustments.

• SBC, or subband codec, is a compression standard that allows Bluetooth devices to reproduce audio at a minimum standard of quality. LC3, or Low Complexity Communication Codec, has superseded SBC.

• Smart Listening, or Adaptive Sound Control, is a Sony headphone feature that automatically adjusts ambient noise levels depending on the listener's environment. It is powered by Sony’s SENSE ENGINE.

• SmartSound detects whether a listener is commuting, in public or in private, and automatically adjusts the audio and/or call quality in response to these surroundings. This technology was developed by audEERING GmbH, a German software company, and is available in certain Jabra headphones.

• Superhuman Hearing is a sound setting that emphasizes subtle sounds (like footsteps or a weapon being reloaded) in certain gaming headsets made by Turtle Beach.

Usability

• JBL headphones with Ambient Aware, or Sony headphones with Ambient Sound Mode, help listeners to remain cognizant of their surroundings by using software to reintroduce a low level of background noise. Some Jabra headphones have a similar feature called HearThrough.

• A Discord Certified headset meets or exceeds the standards of usability, comfortable and audio quality that are enforced by Discord’s quality assurance specialists.

• Dual Audio is a Samsung feature that allows one smartphone (or tablet) to pair with two sets of wireless headphones, then simultaneously broadcast a Bluetooth signal to both. E.g. Listen to the same song.

• Find My Device is a Google service that can locate Pixel Buds that are fast-paired to an Android phone.

• Foldable or collapsible headphones have ear-cups that pivot into the headband for easier storage.

• In-ear detection, or automatic ear detection, is a feature that uses sensors to automatically pause an audio source when an earbud is removed from the ear. Audio resumes when the earbud is placed in the ear again. On-ear detection is a similar feature that is available in some on/over-ear headphones.

• In-line controls are buttons, knobs, sliders and/or flywheels that are built into a headphone’s cable. These controls are often used to adjust volume, mute audio, skip tracks and answer/end phone calls.

• An L-shaped headphone jack is less likely to bend (or snap) at the 3.5mm plug end, however, the 90-degree design puts more stress on the cable itself, which may result in static or a severed connection.

• A multi-platform headset works across platforms like: PC, Mac OS, PlayStation, Xbox, iOS and Android. This interoperability can be achieved through a combination of wireless, USB and 3.5MM connections.

• Multipoint allows a pair of headphones to connect to two Bluetooth sources simultaneously (e.g. a laptop and a smartphone) and to connect to whichever device is currently broadcasting.

• One step pairing, or auto-pairing, is a feature that allows a wireless headphone (or earbuds) to automatically re-connect to a Bluetooth device that it had been previously paired with.

• Passthrough is a headphone feature that doesn't have a formal definition. In some cases, it means that the headphones allow an audio signal to be relayed to another device. In other cases, it means that noise-cancelling headphones can be used passively when they run out of battery. Lastly, passthrough may refer to headphones that record ambient sounds and mix them into what the listener hears.

• Quick Attention Mode makes a rapid volume adjustment that allows the listener to hear ambient sounds. It is activated via a touch sensor on certain Sony headphones.

• ShareMe allows two pairs of compatible Jaybird headphones or earbuds to simultaneously receive the same Bluetooth signal (e.g. listen to the same song). This is achieved by pairing one set of headphones with a Bluetooth device, then using those headphones as a relay that broadcasts to the second set.

• Share mode, or audio sharing, is a generic way to describe any feature that allows two pairs of compatible wireless headphones to listen to the same audio signal.

• Single earbud mode, also called mono mode, allows true wireless earbuds to work independently of one another. To do so, both the left and right earbuds must be individually paired with a Bluetooth device.

• SweatGuard is a proprietary waterproofing found in some Anker Soundcore earbuds. Earbuds with SweatGuard are IP68-rated and have internal sealing which permits an uncovered charging port.

• TalkThru amplifies external voices and lowers the volume of ambient sounds in certain JBL headphones and earbuds. This feature is activated with a button push and is designed to make conversation easier.

• Headphones with touch controls can receive user commands via taps, swipes or other gestures. These commands are recognized via sensors (usually hidden in the earcup), not physical buttons, and may allow the wearer to play, stop, pause or skip audio as well as control volume or answer/end calls.

Voice Assistants

• Headphones and earbuds with Alexa built-in connect directly with the Alexa App on a mobile device.

• Headphones and earbuds with Google Assistant integrated have the voice assistant built into the headphone itself, enabling features like live notifications and realtime foreign language translation.

Weatherproofing

• An IP rating, or ingress protection rating, is a standardized measure of how well a headphone resists dust, moisture, or both. Here are some common IP ratings found in headphones and earbuds:

  • IPX4 is protected against splashing water;

  • IPX5 is protected against low pressure water;

  • IPX6 is protected against high pressure water;

  • IPX7 is protected against short dunks in water up to one meter deep;

  • IPX8 is protected against prolonged underwater exposure as specified;

  • IP54 is protected against dust and splashing water;

  • IP55 is protected against dust and low pressure water;

  • IP56 is protected against dust and high pressure water;

  • IP57 is protected against dust and short dunks in water up to one meter deep;

  • IP58 is protected against dust and prolonged underwater exposure as specified;

  • IP64 is dust tight and protected against splashing water;

  • IP65 is dust tight and protected against low pressure water;

  • IP66 is dust tight and protected against high pressure water;

  • IP67 is dust tight and protected against short dunks in water up to one meter deep; and

  • IP68 is dust tight and protected against prolonged underwater exposure as specified.

Wireless Connectivity

• Bluetooth is a short-wave radio protocol that is the defacto wireless standard found within headphones, headsets and earphones. Here are some common Bluetooth versions:

  • Bluetooth 4.0, adopted in 2010 and deprecated in 2019.

  • Bluetooth 4.1, adopted in 2013 and deprecated in 2019.

  • Bluetooth 4.2, adopted in 2014.

  • Bluetooth 5.0, adopted in 2016.

  • Bluetooth 5.1, adopted in 2019.

  • Bluetooth 5.2, adopted in 2019.

• Class 1 Bluetooth headphones have a radio transmitter that is capable of maximum Bluetooth range (up to 300 feet). The tradeoff for longer range is shorter battery life: Class 1 radios require more power.

• NFC, or near field communication, is a type of ultra-short wave radio that allows smartphones and Bluetooth headsets to pair instantly by tapping the devices together (when both devices support NFC).

• A wireless headphones' range depends largely on the type of Bluetooth radio that it uses. Headphones that use Class 2 Bluetooth radios and can be used around 30 feet away from a broadcasting device.