Updated February 5th, 2021
Audio reviews can be disconcerting. This is often due to the use of a particular vocabulary which can seem like a whole new language. The two glossaries below aim to offer a simple way for reviewers to convey their experience into words while remaining understandable to those new to the world of portable audio.
Analytical – Very detailed, almost to the point of excess.
Attack – The ability of a system to reproduce the attack transients in musical sound. Poor attack makes a system sound slow.
Bass / Low frequencies (20Hz to 500Hz) – The lower end frequency of human hearing. Bass can be measured in quantity (heaviness) and quality (clarity). Sounds that you would typically hear in this range include rumbles from trucks going by, earthquakes, bass drums, acoustic bass. Think of anything sounding deep, with powerful energy.
Boomy – Characterized by pronounced exaggeration of the midbass and, often, dominance of a narrow range of bass frequencies.
Clinical – Sound that is pristinely clean but wholly uninvolving.
Coloration – An audible “signature” with which a reproducing system imbues all signals passing through it.
Control(ed sound) – Tight, detailed, and focused (sound).
Decay – The reverberant fadeout of a musical sound after it has ceased.
Definition (also Resolution) – That quality of sound reproduction which enables the listener to distinguish between, and follow the melodic lines of the individual voices or instruments comprising a large performing group.
Detail – The subtlest, most delicate parts of the original sound, which are usually the first things lost my imperfect components.
Dynamic – Giving an impression of wide dynamic range; punchy. This is related to system speed as well as to volume contrast.
Flat – Deficient in or lacking in soundstage depth, resulting in the impression that all reproduced sound sources are the same distance from the listener.
Forward – A quality of reproduction which seems to place sound sources closer than they were recorded. Opposite of “Laid-back”.
Harsh – Gratingly unpleasant to the ear.
Laid-back – Recessed, distant-sounding, having exaggerated depth, usually because of a dished midrange. Opposite of “Forward”.
Layering – The reproduction of depth and receding distance, which audibly places the rows of performers one behind the other.
Listening Fatigue – A psychoacoustic phenomenon from prolonged listening to sound whose distortion content is too low to be audible as such but is high enough to be perceived subliminally. The physical and psychological discomfort can induce headaches and nervous tension.
Lush – Rich-sounding and sumptuous to the point of wretched excess.
Microphonics – Noises heard in a headphone or earphone/IEM caused by moving/touching the cable. Microphonics is not a quality.
Midrange / Mid frequencies (500Hz to 5000Hz) – The middle frequencies, usually the main body of vocals and acoustic guitars amongst others. The human ear is most sensitive to sound in this range and very small variations can be heard if one frequency is louder than another. Sounds that you would typically hear in this range include sirens, acoustic guitars, violins, flutes and the majority of traditional instruments.
Neutral – Free from coloration.
Open – Exhibiting qualities of delicacy, air, and fine detail. Giving an impression of having no upper-frequency limit.
Smooth – Sound reproduction having no irritating qualities; free from high frequency peaks, easy and relaxing to listen to. Effortless. Not necessarily a positive system attribute if accompanied by a slow, uninvolving character.
Sound signature – See “Timbre” below.
Soundstage – The accuracy with which a reproducing system conveys audible information about the size, shape, and acoustical characteristics of the original recording space and the placement of the performers within it.
Texture – A perceptible pattern or structure in reproduced sound, even if random in nature. Texturing gives the impression that the energy continuum of the sound is composed of discrete particles, like the grain of a photograph.
Timbre – The recognisable characteristic or quality of a sound “signature”.
Thick – Describes sodden or heavy bass.
Thin – Very deficient in bass.
Timbre – The recognizable characteristic sound “signature” of a musical instrument, by which it is possible to tell an oboe, for example, from a flute when both are sounding the same note.
Transparant – Freedom from veiling, texturing, or any other quality which tends to obscure the signal. A quality of crystalline clarity.
Treble / High frequencies (5000Hz to 20000Hz) – The upper frequencies/ higher notes. Sounds that you would typically hear in this range include clapping, birds chirping, and cymbals.
Warm – The same as dark, but less tilted. A certain amount of warmth is a normal part of musical sound.
Weight – The feeling of solidity and foundation contributed to music by extended, natural bass reproduction.
Hardware & Software
Apple Lossless Audio Codec (ALAC) – A reference audio coding implementation and format developed by Apple. Claimed that audio files compressed with this codec will be about half the file size of the original uncompressed data.
Amplifier (Amp) – An electronic device that increases the power of an analog signal to the output or speaker. It is a two-port electrical circuit that utilises electric power from a power supply to increase the amplitude of the signal.
Balanced Armature (BA) Driver – A type of driver most commonly used in hearing aids. Smaller than dynamic drivers and, because of their size, are only available in in-ear monitor (IEM). They are known to be more expensive than dynamic drivers. The driver consists of a miniature arm (armature) inside a coil of wire surrounded by two magnets. The top and bottom magnets determine the movement of the armature. There is often more than one balanced armature driver per earphone using cross-over circuit to split the different parts of sound between the drivers.
Custom In-Ear Monitor (CIEM) – Shorthand for custom-fit in-ear monitors. Usually, custom fit impressions are made at an audiologist and sent to a factory to be made into molds which fit around the driver of the IEM. They result in a tighter fit and more exterior noise isolation.
Digital to Analog Converter (DAC) – A device that converts digital data into an analog signal. Today, most audio is stored as digital data. So before being able to be heard through speakers, the DACs job is to convert this data into an analog signal which is then amplified to a speaker or headphone output.
Digital Audio Player (DAP) – A device that can play digital files. Higher-end DAPs include built-in, high quality digital to analog converters and headphone amps that can drive even power-hungry, high-end headphones. Not to be confused with an iPod or other MP3 playback devices (in this context), high fidelity DAPs can also play high-resolution format files like FLAC, ALAC, WAV and DSD
Direct Stream Digital (DSD) – A trademark used by Sony and Philips for their system of digitally recreating audible signals for the Super Audio CD (SACD). The DSD coding system differs than that of its competitor: PCM. A DSD recorder uses delta-sigma modulation.
Dynamic Driver (DD) – The most common, cheapest, driver. The driver uses the physics of magnetism and electromagnetism to create movement, which leads to sound creation. Also known as moving coil drivers.
Electrostatic Driver – Take advantage of static electricity — the basis of which lies in the fact that like charges repel while opposites attract. The vibrations occur as the diaphragm pushes and pulls against conductive plates (negatively and positively charged respectively) or electrodes, and the air is pushed through the perforations. This action, along with the continuously changing electrical signal, results in sound waves that are understood by the ear. As the driver is quite complex and requires special amplifiers known as energizers, they are usually found in the high-end open-back headphones. Electrostatic drivers are relatively uncommon and are more expensive.
Free Lossless Audio Codec (FLAC) – An audio coding format for lossless compression of digital audio. It is also an open format with royalty-free licensing and a reference implementation which is free software. FLAC has support for metadata tagging, album cover art, and fast seeking.
Headphone – A stereo speaker system worn either on or over the ears.
High-Resolution Audio (Hi-Res Audio) – Hi-Res Audio is lossless audio capable of reproducing the full range of sound from recordings that have been mastered from better-than-CD quality music sources, a sound that closely replicates the quality that the musicians and engineers were working within the studio at the time of recording.
In-Ear Monitor (IEM / Earphone) – A stereo speaker system worn inside the ear.
Impedance – Indicates in Ohm (Ω) how much power is required for the driver. The higher the impedance, the more power is required to get the maximum quality and volume of sounds out of the driver. Electrical resistance to the flow of current in an AC circuit. The higher the impedance of the headphone, for instance, the less current will flow through it.
Lossless – Refers to music file compression that does not remove data to compress the file such as ALAC, DSD, FLAC, WAV or MQA.
Lossy – Refers to music file compression methods that remove the least audible sounds from music files to compress them. Compression cannot be reversed or uncompressed like in the case of lossless formats. Examples include MP3, AAC, Ogg, etc.
Master Quality Authenticated (MQA) – A lossless codec of about one-third the size of FLAC formatting. It applies a digital fingerprint to guarantee a file was sourced from the original master recording. MQA files are backward compatible with FLAC decoders but require MQA decoders to unlock their full benefit. Used by streaming services like Tidal.
Ohm (Ω) – Unit of measurement for electrical resistance or impedance.
Pulse-Code Modulation (PCM) – The standard form of digital audio in computers and CDs. It is a method used to digitally represent sampled analog signals. A PCM stream has two properties that determine the stream’s fidelity to the original analog signal: the sampling rate, which is the number of times per second that samples are taken; and the bit depth, which determines the number of possible digital values that can be used to represent each sample.
Planar Magnetic Driver – Often featured in open-back, over the ear headphones. The drivers are extremely thin and are usually located in high-end headphones. The drivers are based on a similar principle to that found on the dynamic driver headphones – using magnetic fields to produce sounds. And since the whole diaphragm has to be evenly vibrated, larger or more magnets are used and this adds on to the weight of the headphone. It also results in the need for more power from the audio source or purchasing an external amplifier. Also referred to as orthodynamic driver by Yamaha.
Senstivity – The amount of sound output in headphones, measured in decibels (dB). For reference, 86dB is considered low, while anything above 110dB is considered high.
Waveform Audio File Format (WAV) – More commonly known as WAV due to its file extension, is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs. The WAV file is an instance of a Resource Interchange File Format (RIFF), defined by IBM and Microsoft. Though a WAV file can contain compressed audio, the most common WAV format is uncompressed audio in the linear pulse-code modulation (LPCM) format. LPCM is also the standard audio coding format for audio CDs.