Audio Glossary: HiFi Terms Explained
Plain-English definitions of the audio terms you'll meet while shopping. Deep dives live in our buying guides.
DAC (Digital-to-Analog Converter)
The chip or device that turns digital audio (files, streams) into the analog signal headphones need. Phones have one built in; a dedicated DAC usually measures better and drives harder loads.
Dongle DAC
A thumb-size USB-C DAC/amp that plugs into a phone or laptop and replaces its weak headphone output. The single biggest budget upgrade for wired listening.
DAP (Digital Audio Player)
A dedicated portable music player with audiophile-grade DAC and amplification, used instead of a phone for higher output power and cleaner sound.
IEM (In-Ear Monitor)
An earphone that seals inside the ear canal. Compared to earbuds, IEMs isolate noise passively and position drivers precisely; most wired audiophile earphones are IEMs.
Driver
The unit inside a headphone that produces sound. Common types: dynamic (moving coil), balanced armature, planar magnetic, electrostatic — each with different strengths.
Dynamic driver
The classic cone/dome driver. Naturally strong bass punch and coherent timbre; quality varies more with implementation than with size.
Balanced armature (BA)
A tiny driver originally from hearing aids, used in multiples inside IEMs. Fast and detailed, but usually needs several units to cover the full frequency range.
Planar magnetic
A driver using a thin film diaphragm between magnets. Known for speed, low distortion and effortless detail; usually needs more amplifier power than dynamics.
Bone conduction
Headphones that vibrate your cheekbones instead of covering your ears, leaving them open to surroundings — the go-to design for runners and cyclists (e.g. SHOKZ).
ANC (Active Noise Cancellation)
Microphones sample outside noise and the headphone plays inverted sound to cancel it. Great for commutes and flights; strength varies enormously between models.
Open-back
Headphones with perforated outer cups. Wider, more natural staging, but they leak sound both ways — best used in quiet rooms.
Closed-back
Sealed outer cups. Better isolation and bass impact, at some cost to stage width. The right pick for offices and shared spaces.
Soundstage
The perceived size and space of the music — how far instruments seem to extend beyond your head. Open-backs and certain IEM tunings excel here.
Imaging
How precisely you can locate each instrument within the soundstage. Critical for gaming and orchestral music.
Frequency response
A graph of how loud a headphone plays each frequency from bass to treble. The single most useful objective clue to how something sounds.
Harman target
A research-derived frequency response curve that most listeners prefer. 'Harman-tuned' means a safe, mass-appeal sound signature.
Impedance (Ω)
Electrical resistance of a headphone. High-impedance models (150Ω+) need more voltage; low-impedance IEMs are easy to drive but sensitive to source hiss.
Sensitivity
How loud a headphone plays per unit of power (dB/mW) or voltage (dB/V). Low sensitivity + low impedance (many planars) demands real amplifier current.
Balanced output (4.4mm / 2.5mm)
A connection carrying separate positive and negative signals per channel. Its practical benefit on portables: roughly double the output power versus 3.5mm.
LDAC
Sony's high-bitrate Bluetooth codec (up to 990 kbps) — the closest wireless gets to lossless. Both source and earphone must support it, and it's often off by default.
aptX / aptX HD
Qualcomm's family of Bluetooth codecs, a step above SBC/AAC on supported Android devices.
Hi-Res Audio
Certification for gear that reproduces frequencies above 40kHz and files beyond CD quality (24-bit/96kHz+). Nice to have; implementation matters more than the badge.
Tuning nozzles
Swappable metal nozzles on some IEMs (e.g. SIMGOT EA500) that change the frequency response — effectively several sound signatures in one purchase.
Tips (ear tips)
The silicone or foam sleeves on IEM nozzles. The cheapest, most powerful tweak: fit and bore width measurably change bass seal and treble.
Burn-in
The idea that drivers change sound after hours of playback. Measurable effects are small; most perceived change is your brain adapting. Buy for how it sounds now.