Audio Terms and Definitions copied from Moon Audio.
This should be pinned somewhere as a reference or made better by someone with more skills than I.
AES / EBU – Audio Engineering Society / European Broadcasting Union – (Also known as AES3) A standard for the exchange of digital audio signals between professional audio devices. An AES3 signal can carry two channels of PCM audio over several transmission media including balanced lines, unbalanced lines, and optical fiber.
Airy – Describes the space and openness of the product usually associated with open back headphones and live music.
ALAC – Apple Lossless Audio Codec – 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.
Ambience – The overall impression, feeling, or mood evoked by an environment or acoustical space, such as the performance hall in which a recording was made.
Amp – Shorthand for an amplifier. An electronic device that increases the power of, in this case, an analog signal to the output or speaker. It is a two-port electrical circuit that utilizes electric power from a power supply to increase the amplitude of the signal.
Amplitude – The displacement of a wave from its mean value. In sound, it refers to the extent which air particles are displaced and is experienced as the loudness of sound. The higher the amplitude, the louder the sound.
Analog (Audio) – Sound that has been recorded onto an analog medium like vinyl or tape. The recording on the medium, however, can have small imperfections that can cause audio artifacts in the playback.
APE – From Monkey’s Audio – A free and efficient high resolution codec that provides lossless audio data compression. (APE files can be decompressed into identical copies of the original digital recording.) APE has better compression rates than FLAC but has limited support and is taxing to decode.
ASP – Analog Signal Processing-An analog signal is one represented by a continuous stream of data, in this case along an electrical circuit in the form of voltage or current. Analog signal processing then involves physically altering the continuous signal by changing the voltage, current or charge via various electrical means. Examples include crossover filters in loudspeakers, “bass, treble and volume” controls on stereos and “tint” controls on TVs. Also considered capacitors, resistors, and inductors (passive), and active elements such as transistors/operational amplifiers.
Attenuator – A device or component that lowers the volume of an audio signal (example: volume control on an amplifier).
Audiophile – An individual who is enthusiastic about high-fidelity sound reproduction. An audiophile seeks to reproduce the sound of a live musical performance, typically in a room with great acoustics.
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Balance – Usually the tuning of the earphone. A well-balanced headphone would not have one particularly dominant frequency, but rather all would be “balanced.”
Balanced (Audio) – a method of interconnecting audio equipment using impedance-balanced lines. Balanced connections use three-conductor connectors, usually an XLR or TRS jacks (a plus, a minus, and a ground).
Balanced Armature Driver – A type of driver most commonly used in hearing aids. Balanced armature drivers are designed to only reproduce a set part of the audible spectrum of sound, and as a result, are far more detailed in their sound reproduction within their set piece of the spectrum of sound. Because of this, it is generally necessary to use more than one balanced armature driver per earphone to cover the entire audible spectrum of sound. However, due to the need for a cross-over circuit to split the different parts of sound between the drivers, many would say that balanced armature drivers are less natural sounding than dynamic drivers.
Bass – The lower end frequency of human hearing. Bass can be measured in quantity (heaviness) and quality (clarity). Other bass descriptors are “muddy” and “boomy.”
Bit Rate – Refers to how much data is being stored per second (digital audio).
Bit Depth – Refers to how much data is recorded per sample (digital audio). The more information (higher sample/bit rates and depth) the better quality and larger the file size, generally speaking.
Bloat – A lack of definition and clarity in the mid-bass range. Overly-accentuated bass makes the signature sound heavy and poorly tuned. Bloat is commonly associated with dark, or overly warm, sound signatures.
BNC – A type of locking connector used for digital connections.
Breakup – When different points on the surface of a diaphragm begin to move out of sync, causing distortion. Breakup often occurs in dynamic drivers at high volumes as forces on the diaphragm increase. Breakup is less likely to occur at lower volumes or in planar magnetic or electrostatic headphone drivers.
Bright/Brightness – A boost in the upper frequencies or upper-mid range. Brightness is a feature enjoyed by many but walks a thin line to becoming unpleasant due to a potential of treble peaking.
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Cable Attachment-Style: Wired headphones come in two styles:
- Detachable and interchangeable.
- Hardwired. Hardwired headphones can be “Hacked” for better performance.
Caps – Shorthand for a capacitor. Capacitors store energy inside a device temporarily, which can have a number of functions: in an amp power supply, DC coupling, tone controls, and filtering.
Circum-aural – Refers to Full-Size headphones that fit over-the-ear.
Coloration – the effect of a device on the music signal. The opposite of “neutral.” Various aspects can affect the tone, responsiveness or the frequency response of the music/audio.
Congestion – Poor clarity caused by overlapping sounds. Congested sound signatures lack detail and clarity, making it hard to hear separate instruments and may also be called muddy or muffled.
Cranial Geometry – The unique contours of the human cranium that can impact a headphone’s “fit” or the level of comfort around the user’s head. This makes certain headphones a better fit for users with varying head shapes and sizes. If the geometry of the headphone does not align with a user’s unique head and ear geometry, this can impact the headphone’s “sealing condition,” and cause the sound to “leak” out. When this occurs, the headphone’s impressive sense of presentation and comfort-level may be compromised, entirely.
Crisp – Clear.
Cups – Referring to the casing on the outer sides of the drivers on over/on-ear headphones. On closed-back headphones, they are referred to as “cups.” On open-back headphones, they are referred to as “grills.”
Customs – 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. Also known as “CIEM’s.”
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D/A – Digital to Analog – A shorthand way to show the digital to analog conversion path.
DAC – Digital to Analog Converter – 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. DACs are found in most of today’s electronics, but standalone or external DACs are usually far more superior than their internal factory counterparts.
DAP – Digital Audio Player – Simply put, 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 standard MP3 playback devices (in this context), high fidelity DAPs can also play high-resolution format files like WAV and FLAC.
Dark/Darkness – Usually described when the higher frequencies are less prominent.
Decay – Describing the fade effect/length of a sound or note.
Decibel (dB) – A measure of the magnitude of sound, or more simply, how loud something is.
Depth – Describing how far away the instruments spacing is from back to front.
Detail – The subtlest, most delicate parts of the original sound, which are usually the first things lost my imperfect components.
Digital (Audio) – Sound that has been recorded in or converted to digital data. In digital audio, the signal has been encoded as numerical samples in a continuous sequence. In a CD, samples are taken 44,100 times per second, each with 16-bit sample depth.
Driver – The speaker within a headphone or earphone. There are many varying sizes, qualities and types.
DSD – Direct Stream Digital – 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.
DSP – Digital Signal Processing – As audio signals may be represented in either digital or analog format, processing may occur in either domain. Analog processors operate directly on the electrical signal, while digital processors operate mathematically on the digital representation of that signal. A digital representation expresses the audio waveform as a sequence of symbols, usually binary numbers. This permits signal processing using digital circuits such as digital signal processors, microprocessors and general-purpose computers.
Dynamic Driver – The most common driver type, dynamic drivers are designed to be able to cover most of the spectrum of audible sound. They are typically larger and less detailed than their more expensive counterparts, balanced-armature drivers. They use a static magnetic field to oscillate the voice coil and create sound waves.
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Earphone/Earbud/In-Ear Monitor (IEM) – A stereo speaker system that is worn inside the ear.
Electrostatic Driver – Headphone driver featuring an extremely thin diaphragm suspended between two electrified plates. They use static electricity to move the diaphragm, meaning there are no moving parts inside. Electrostatic drivers are virtually distortion-free but expensive and require special amplifiers.
EQ – Short for equalization. Using software or hardware to adjust the relative volume of frequencies in audio.
Ergonomic Flexibility – A headphone’s ability to fit within a scenario for any type of application, whether that be in the home, on-the-go or professionally.
Ergonomic Scenario – The situation or application where a headphone’s use is optimized for the greatest performance and the best sonic results.
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FLAC – Free Lossless Audio Codec – 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.
Forward – A more intense overall presentation of the sound. Described as opposite of laid back and relaxed.
Frequency Range – A range of frequencies stated without level limits.
Frequency Response – A measurement of how accurately a component reproduces audio frequencies listed as a variance within a set range. A frequency response of 20Hz-20kHz ±0.5 will increase or decrease a signal within that range by up to 0.5 decibels. An ideal frequency response is flat (or closest to zero), meaning the output is identical to the input.
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Gain – The factor by which the audio signal is increased by an amplifier. Normally expressed in dB, the signal is either increased or decreased by volts in/volts out.
Glassy – Described as very bright.
Grill – Refers to the outer casing on an open-back headphone. The grill is located on the outside of the drivers where the headphone is open or semi-open.
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Harsh – Usually used to describe the upper-mid to upper frequencies when you get too much treble. An unpleasant quality.
Headphone – A stereo speaker system that is worn either on or over the ears.
HIFI – High Fidelity – This term is often used to refer to the high-quality reproduction of sound.
HiFi v. LoFi – Generally speaking, if high fidelity is the accurate and realistic representation of the original recording, low fidelity would refer to when the sound quality is lower than the usual contemporary standard. The imperfections of the recording and production are audible, along with inconsistencies in notes, environmental interference and hardware imperfections are all appropriate and expected in a low fidelity environment.
High-end Audio – Refers to the sound equipment used by audiophiles; typically, well made for accurate reproductions of sound recordings. High-end components include turntables, digital to analog converters, equalization devices, preamps and amplifiers, speakers, subwoofers, etc. Acoustic room treatment is also considered since it does well at acoustically optimizing a designated space for listening.
HRA – High-Resolution Audio - Hi-Res Audio (HRA) 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.
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IC – Short for Interconnect Cable. Two analog connections, terminating in either XLR or RCA plugs, for Right and Left stereo audio channels.
IEM – Also see Earphone. Acronym referring to “In-Ear-Monitor.” There are two types 1.) Pre-formed “Universal IEMs” or Earphones, which are pre-molded to fit inside the ear canals, universally, and 2.) custom IEMs. Custom IEMs are custom-molded by an audiologist to fit the unique impressions of a wearer’s ear canal.
Impedance – Indicates 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.
Isolation – Created when a tight “sealing condition” around the ears effectively prevents sound from leaking out.
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Jitter - A loss of a sample or block of samples in a bitstream during playback in a digital device, introducing noise. It can be caused by a number of factors including sync/word clock error or even buffer issues with the interface. Regardless, it happens with all digital devices and introduces noise, so that is why it’s important to have more data or higher quality recordings for playback to minimize jitter.
Judgement - A listener’s assessment of how wekk his or her perception of a sonic element measures up to their concept of perfection.
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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.
Listening-Style – The way a user prefers to listen to music. Typically, users may prefer to listen more analytically, or they may prefer to relax and “get lost” in the music. There’s no right or wrong way to listen to music.
Lossless – Refers to music file compression that does not remove data to compress the file. Examples include FLAC, WAV, MQA, etc.
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.
Low-Level Detail – The subtlest elements of musical sound, which include the delicate details of instrumental sounds and the final tail of reverberation decay.
Lush – A rich tone and usually with some warmth to the overall presentation.
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Microphonics – Frictional sound heard in a headphone caused by movement or rubbing of the cable against itself or other objects. The rustling noise comes from physical vibrations being converted into electrical signals. This is also called cable noise and is minimized with proper shielding in higher-quality cables.
Moving Armature Driver – A relatively new type of driver. Moving armature drivers aim to eliminate the need to use multiple balanced armature drivers in an IEM by extending their effective frequency response.
MP3 – MPEG-1/2/2.5 Audio Layer III – A specific and common coding format for digital audio. Popular for smaller file sizes and customizable parameters.
MQA – Master Quality Authenticated - 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.
Muddy – An unclear presentation of the sound. The opposite of clean or clear.
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Nasal - Reproduced sound having the quality of a person speaking with their nose blocked. Closed off; a measured peak in the upper midrange followed by a complimentary dip.
Natural - In relationship to the relative perceived realism of the music.
Neutral - free from coloration.
Noise - Any spurious background sounds, usually of a random or indeterminate pitch: hiss, crackle, ticks, pops, etc.
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Ohm – Unit of measurement for electrical resistance or impedance.
Opamp – Operational Amplifier – A high-gain electronic voltage amplifier with a differential input and usually single-ended output. By doing this, an operational amplifier produces an output potential that is typically hundreds of thousands of times larger than the potential difference between its input terminals. The popularity of the operational amp as a building block in analog circuits is due to its versatility.
Openness – Described as good width and depth in the presentation of sound. Plenty of room between the instrumentation.
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Pads – the earpads or cushioning on headphones.
PCB – Printed Circuit Board – Electrical components are generally soldered onto the printed circuit board to both electrically connect and mechanically fasten them to it. Used in most electronic products.
PCM – Pulse-Code Modulation – 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 – Popular headphone driver featuring a series of magnets on both sides of a very large, flexible diaphragm containing tiny, electrically charged wires. Planar magnetic drivers are precise with a wider range but tend to be large and quite heavy. Magneplanar, isodynamic, and orthodynamic drivers all operate on this planar magnetic design.
Preamp – Shorthand for a preamplifier. The preamp acts as a switch, routing one or more signals to the amplifier. It reduces noise and interference while boosting the signal and adjusting the voltage for volume control to the amplifier. Preamplifiers also usually allow a user to switch between sources (radio, tape, CD, etc.).
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Qualifier - An adjective which this listener attaches to an observed sonic imperfection in order to convey a sense of its magnitude. Example: muddy, harsh, undefined, etc.
Quality - How the music is perceived in relation to how it should sound (towards the goal of perfection).
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RCA – A type of coaxial connector used for unbalanced analog connections. The center pin is used for the signal and the outer sleeve is connected to the ground.
Resistance – The physical property of elements to resist the flow of electrons, and is measured in units of Ohms.
Reverb – Short for reverberation. A diminishing series of echoes spaced sufficiently closely in time that they merge into a smooth decay.
Rolloff – Also known as rollout. A frequency response which falls gradually above or below a certain frequency limit. By comparison, the term “cutoff” implies an abrupt loss of level above or below the frequency limit.
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Sample Rate – Refers to how many samples of data were taken in a second (digital audio).
Sealing Condition – This feature helps lock in the sound (called “isolation”), and prevents it from leaking outside of the headphone.
Sense of Presentation – The way a sound is oriented or presented to the listener. It affects the way listeners perceive the locale of a sound’s source and provides a sense of where the sound is being produced.
Sensitivity – The amount of sound output in headphones, measured in decibels (dB). Sensitivity measures how loud a headphone is at a set power level, typically 1 milliwatt. Sensivity may also be represented as Efficiency or Sound Pressure Level (SPL).
Sibilant – The high unpleasant peaks that are usually unpleasant to the ear if too prevalent.
Smooth – Describing the quality of sound reproduction having no irritating qualities; free from high-frequency peaks, and relaxing to listen to. Not necessarily a positive system attribute if accompanied by a slow, uninvolving character.
Sound Signature – The unique intrinsic sound quality of a headphone, music player, DAC, or audio cable. Some audio products emphasize the higher treble ranges while others strengthen the bass. This overall sound profile of audio devices helps audiophiles fine-tune the listening experience by pairing the right headphone cable, DAC, or music player with their headphones. Learn more about sound profiles using this Guide to Sound Signatures.
Soundstage – A description of the 3D sound space that a driver makes. A wide soundstage allows a listener to discern different positions for various sounds, lending a hand in making the sound more realistic. The bigger the soundstage, the better.
Source – The first device in the signal chain that sends out an analog signal, such as a CD player or media player.
S/PDIF – Stands for Sony/Philips Digital Interconnect Format (more commonly known as Sony Philips Digital Interface).
Supra-aural – Refers to Fit-types that rest against the user’s ears, or “on-the-ear.” This is one of the most common Fit-types in the consumer market.
Synergy – The interaction or cooperation of two or more audio components in an audio system, which, when combined produce a combined effect greater than the sum of their separate effects. Example: the synergy between a DAC and a headphone amp.
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Texture/Texturing – 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.
THD – Stands for Total Harmonic Distortion. A measurement of the degree to which a piece of equipment distorts the signal.
Timbre – the basic tone of a note, or the recognizable characteristic sound signature of an instrument.
Tonality – In referring to music, tonality is the quality of the instrument’s tone. In referring to audio, it refers to the reproduction of the sound and accuracy of the original timbres.
Transparent – Described as clarity in the sound presentation; being able to distinguish details and qualities.
TRS – Tip Ring Sleeve connector. The most common connector used on headphones. 3.5mm (/8”) and 6.3mm (1/4”) connector sizes.
Tube/Tube Amp – Vacuum tube, used for amplification prior to the invention of the transistor. Popular in amplifiers due to their pleasant harmonics and coloration of the music. Tube amplifiers use tubes in a section of the design for either amplification or power rectification.
Turntable – Derived from the phonograph, the original device was used for the recording and reproduction of sound. In its later forms, it is also called the gramophone (since 1887) and later the record player (since the 1940s). The turntable today is the device used to playback the record. The tonearm holds the pickup cartridge over the groove, as a pivoted lever with a counterbalance to maintain tracking pressure.
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Uncolored - Free from coloration.
Upper - In relation to the full spectrum or specific range; top half of specified range.
Upper Bass - Denoted as the range of frequencies from 80 - 160Hz.
Upper Highs, Treble - Denoted as the range of frequencies from 10 - 20kHz.
Upper Mids, Middles, Midrange - Denoted as the range of frequencies from 650 - 1300Hz.
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Voltage – The electromotive force or pressure that ‘pushes’ large number of electrons, measured in units of volts.
Veiled - Lack of full clarity due to noise or loss of detail from limited transparency.
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Warm/Warmth – Engaging vocals, bumped mid-bass and clear midrange. Full sounding with clarity.
Watt – Voltage times current. An expression of the rate of energy usage. Sometimes noted with R.M.S. meaning Root Mean Square.
Weight – The feeling of solidity and foundation contributed to music by extended, natural bass reproduction.
Width – The apparent lateral spread of a stereo image. If appropriately recorded, a reproduced image should sound no wider or narrower than how it sounded originally.
WMA – Windows Media Audio Lossless – A proprietary lossless audio data compression technology developed by Microsoft which competes with FLAC and Apple Lossless Audio Codec (ALAC).
WAVE – Waveform Audio File Format – 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.
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XLR – A connector commonly used in professional audio, typically with a three or four-pin configuration used primarily in audio for balanced connections. With 3-pin plugs and sockets, one pin carried the in-phase signal, another the out of phase and the third pin is the ground. On headphones there is no ground; the 4-pin XLR, when used on headphones, runs L+ L- R+ R-.