In-Ear Earphone Glossary: 29 Terms

Reviewed 17 Oct 2026 · Data from KZ’s official spec sheetsFor: Listening to music Recording and mixing at home Playing live and rehearsing

The terms you see on in-ear spec sheets, explained in one or two sentences and linked to the guide where we cover them in depth. Each model’s data comes from KZ’s official spec sheets (kz-audio.com).

Passive isolation · Ear tips · Headphone amplifier · Balanced armature (BA) · Detachable cable · Active noise cancelling (ANC) · Click · 2-pin connector · Bluetooth codec · DAC · Driver · Dynamic driver (DD) · Planar driver · Sound signature · Harman (curve) · Hybrid · Impedance · Tuning switches · 3.5 mm and 4.4 mm jack · Latency · Monitor mix · MMCX · In-ear monitors (IEM) · IEM bodypack · Pin B and Pin C · Frequency response · Sensitivity · TWS · Ways

Passive isolation: The outside noise an in-ear blocks simply by sealing the ear canal with the ear tip. No electronics involved: it depends on how well they fit. It is what lets you hear yourself in the rehearsal room without turning the volume up as much. More in how to wear in-ear earphones properly.
Ear tips: The silicone or foam tips that go on the earphone nozzle. They come in sizes (S, M, L) and they create the seal: if the size isn’t yours, you lose bass and isolation.
Headphone amplifier: A device that gives headphones more power. In-ears are usually easy to drive and work fine with a phone, a mixing desk or a bodypack without a separate amp. More in impedance and sensitivity.
Balanced armature (BA): A very small driver in which a reed moves between magnets. It is efficient and precise, but each armature covers one part of the sound well, which is why all-armature models use several, split across ways. More in driver types.
Detachable cable: A cable that detaches from the earphone. If it breaks or you want a different one (with a mic, USB-C, longer), you replace the cable, not the earphones. More in cables for KZ earphones.
Active noise cancelling (ANC): A system with microphones and electronics that creates an inverted signal to cancel noise. It is a feature of some wireless earphones; wired in-ears isolate passively, through the seal.
Click: A metronome track the drummer (or the whole band) hears in their in-ears to play in time, especially with backing tracks or sequences. More in IEMs for drummers.
2-pin connector: The most common detachable cable connector on in-ears: two thin pins that plug into the earphone. Almost every wired KZ uses it. More in Pin B or Pin C.
Bluetooth codec: The format used to compress and send audio over Bluetooth (SBC, AAC, aptX, LDAC…). Both devices must share the codec; otherwise the basic one is used.
DAC: Digital-to-analogue converter: it turns digital audio into the signal that drives the earphones. A phone without a jack needs one, usually built into a USB-C to jack adapter. More in wired earphones on a phone without a jack.
Driver: The part that turns the electrical signal into sound. An earphone can have one or several, of different types (dynamic, balanced armature, planar).
Dynamic driver (DD): A driver with a diaphragm moved by a coil inside a magnet, like a miniature speaker. It is the most common type and usually gives the most punch in the bass. More in driver types.
Planar driver: A driver with a very thin diaphragm carrying a printed circuit, placed between magnets. It moves more evenly than a dynamic diaphragm. More in KZ’s planar models.
Sound signature: How an earphone balances bass, mids and treble: “V-shaped” (boosted bass and treble), neutral, warm… The versions of some KZ models (Improved Bass, Balanced, Harman) change that signature.
Harman (curve): A reference curve from Harman’s research into which response most listeners prefer. When a KZ comes in a “Harman” version, KZ says it is tuned to that reference.
Hybrid: An earphone that combines driver types, usually one or more dynamic drivers for bass and balanced armatures for mids and treble. More in driver types.
Impedance: The resistance the earphone presents to the signal, in ohms (Ω). With low impedance, like most in-ears, a phone or a bodypack drives them without trouble. More in impedance and sensitivity.
Tuning switches: Small switches on the shell of some KZ models that change the sound (more or less bass or treble). More in KZ tuning switches.
3.5 mm and 4.4 mm jack: The 3.5 mm jack is the classic headphone plug. The 4.4 mm one is the balanced version used by some DACs and players; it needs a cable with that plug.
Latency: The delay between a sound happening and you hearing it. Bluetooth adds a delay you notice when playing, which is why live monitoring uses a cable or a wireless IEM system, not Bluetooth.
Monitor mix: What each musician hears in their in-ears: a send from the desk with their instrument, the vocals, the click… adjusted to taste. More in in-ear monitors for live use.
MMCX: Another detachable cable connector, round and able to rotate. KZ mainly uses 2-pin, so an MMCX cable won’t fit most KZ models.
In-ear monitors (IEM): Earphones that sit inside the ear canal, used by musicians to hear themselves on stage instead of floor wedges.
IEM bodypack: The receiver a musician wears on their belt: it receives their monitor mix (wired or wireless) and has its own volume. The in-ears plug into the bodypack.
Pin B and Pin C: The two versions of the 2-pin connector KZ uses. They differ in the shape of the connector, so it is worth knowing which one your KZ has before buying a cable or an adapter. More in Pin B or Pin C.
Frequency response: The range of sounds, from bass to treble, an earphone reproduces, in hertz (for example, 20 Hz–20 kHz). It tells you the range, not how it sounds within it.
Sensitivity: How loud an earphone plays with a given power (dB/mW). The higher it is, the more volume it gets from a phone or a bodypack. More in impedance and sensitivity.
TWS: True Wireless Stereo: Bluetooth earphones with no cable at all, not even between the two buds. More in TWS or adapter.
Ways: How many parts the sound is split into across an earphone’s drivers. In 3-way in-ears, some drivers handle the bass, others the mids and others the treble.