Pro Audio Reference


Pro Audio Reference (Q)


q (lower-case) Physics. The symbol for charge.

Q (upper-case) Quality factor. Filters. The selectivity factor defined to be the ratio of the center frequency f divided by the bandwidth BW. See the RaneNote Constant-Q Graphic Equalizers; also download "Bandwidth vs. Q Calculator" as a zipped Microsoft Excel spreadsheet in the Rane Library.

Q (upper-case) Quality factor. Loudspeakers. Used to connote the directivity, or a measure of the directional characteristic of a loudspeaker, and is called the Directivity Index, either measured in decibels, or as a dimensionless value of Q. See "A game of numbers" by Joe Brusi for more details.

Q-8 RCA's name for their 4-channel, eight-track tape cartridges, the world's first (and last).

qanbus Musical Instrument. A short-necked fretless flute indigenous to Yemen.

qanoun Musical Instruments. Arabic dulcimer. Contrast with: Quanoon.

qawwali A style of Muslim devotional music, associated particularly with Sufis in Pakistan, characterized by a fervent, often improvisatory vocal delivery and with an accompanying rhythm articulated on drums and harmonium; a song in this style. [OED]


QED (quod erat demonstrandum) Latin. Mathematics. Literally, "which was to be demonstrated." Used to connote the end of a mathematical proof.

Qi (pronounced "chee") From Asian philosophy, meaning "vital energy." The name adopted for a standard universal battery charging system for mobile devices whereby any Qi-compatible device or adapter can be charged with any Qi-compatible charging pad.

qin also guqin A Chinese musical instrument dating from 1000 BC similar to a zither; common name for most Chinese stringed instruments. Also Qin dynasty. See yangqin.

qix Online jargon shorthand for "quick."

QLED (quantum-dot LED) also seen as QD LED. Latest LED technology based on quantum dot semiconductor nanocrystals.

QoS (quality of service) Today's usage: "Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow." [From Wikipedia; hit link.] Original usage: 1. The performance specification of a communications channel or system. It may be quantitatively indicated by channel or system performance parameters, such as signal-to-noise ratio (S/N), bit error ratio (BER), message throughput rate, and call blocking probability. 2. A subjective rating of telephone communications quality in which listeners judge transmissions by qualifiers, such as excellent, good, fair, poor, or unsatisfactory. [From Federal Standard 1037C].

QR code (Quick Response code) A matrix barcode readable by devices with cameras, i.e., smart phones, tablets, etc.

QRD (quadratic residue diffusor) Another name for a Schroeder diffusor. Hit the link for more details and also see: diffusers.

QS Sansui's name for their quadraphonic sound system using a proprietary matrixing algorithm for encoding four-channel sound down to two-channels. Compare with SQ.

QSound The name of a Canadian company and its proprietary and patented 3D sound technology. Designed for two channel playback systems, QSound finds success in the computer and arcade game markets, as well as movie theaters. Using advanced signal processing techniques, QSound adds localization cues to the original material. Since loudspeakers and headphones create quite different playback environments, different algorithms exist for each. QSound allows the music producer to locate specific sound events in virtual positions outside the physical locations of the two loudspeakers. The effect is primarily one of widening the sound field. QSound works best when the listener is positioned in the sweet spot located equidistant between the speakers.

QT The state of being secret or confidential: told me the story on the QT. [AHD] Also online jargon shorthand for "cutie."

QTC (quantum tunnelling composite) Pressure sensors based on quantum physics. Finding use in touchscreens, among other applications.

QTR Abbreviation for quarter.

QTY Abbreviation for quantity.

quackery The statement floating about cyberspace that a duck's quack does not echo and no one knows why. See Salford Acoustics Experiment.

Quad 8 See: Q-8.

quad flat pack The most commonly used package in surface mount technology to achieve a high lead count in a small area. Leads are brought out on all four sides of a thin square package.

quadlet Computers. Four bytes (32 bits) of data. [IEEE]

quad mic cable See: cables.

Quadradisc See: CD-4.

quadraphonic sound Coined in the '70s, the original term for surround sound.

quadratic equation Mathematics An equation in which one or more of the terms is squared but raised to no higher power, having the general form ax² + bx + c = 0, where a, b, and c are constants. [AHD]

quadratic residue diffuser A type of Schroeder diffuser consisting of a plane surface with an array of parallel slots all the same width but with varying depths based on a prime number mathematical sequence.

quadrature A state of separation or relationship equal to 90°. For example, two same frequency sine waves one-quarter wavelength apart are in quadrature. A phase difference equal to one-fourth of a period.

quadruple-play network A network offering mobility in addition to audio, video and data.

quadrupole sound source Acoustics. Quadrupole is defined as a multipole of order two, therefore two opposite dipoles make up a quadrupole source.

quaff To drink (a beverage) heartily: quaffed the ale with gusto. [AHD]

quale (plural form: qualia) A property, such as whiteness, considered independently from things having the property. [AHD] "Examples of qualia include the pain of a headache, the taste of wine, or the perceived redness of an evening sky." [from link]

quality factor See Q.

Quanoon Musical Instruments. Egyptian dulcimer. Contrast with: Qanoun.

quant Slang An expert in the use of mathematics and related subjects, particularly in investment management and stock trading. [Probably short for quantitative.] [AHD]

quantal Physics. 1. Of or relating to quanta, quantum mechanics, or a quantized system. 2. Existing in only one of two possible states. [AHD]

quantic Mathematics. A homogeneous polynomial having two or more variables. [AHD]

quantization distortion Same as quantization error below.

quantization error Error resulting from quantizing an analog waveform to a discrete level. It is the difference between the actual value of the analog signal at the sampling instant and the nearest quantization value. Therefore, in general, the longer the word length, the less the error, because there are more step sizes to choose the closest. See also SQNR and the RaneNote Digital Dharma of Audio A/D Converters.

quantization The process of converting, or digitizing, the almost infinitely variable amplitude of an analog waveform to one of a finite series of discrete levels. Performed by the A/D converter. See also SQNR and the RaneNote Digital Dharma of Audio A/D Converters. [The name derives from quantum physics, where electrons orbit an atom's nucleus at fixed distances and are never found in-between.]

Quantizer™ Trademark of M.I.T. for the work conceived and developed by Juliana Cherston and Ewan Hill that converts high energy physics data from the ATLAS/CERN project into real-time audio. Details here.

quantum Physics. The smallest amount of a physical quantity that can exist independently, especially a discrete quantity of electromagnetic radiation. [AHD]

quantum dot A confined and isolated atom such that the removal or addition of a single electron can be detected, i.e., its properties change in a detectable manner — the ultimate memory cell. In nanotechnology, they are called quantum bits or qubits.

quantum entanglement Physics. Einstein called entanglement "spooky action at a distance." Hit the link for a clear simple explanation.

quantum microphone A new technology for detecting "... sound at the level of quietness of quantum mechanics." Developed by scientists at Chalmers University of Technology in Sweden and is based on a single-electron transistor.

quantum noise Physics. Any noise attributable to the discrete nature of electromagnetic radiation. Shot noise is one example.

quantum tunneling composite See: QTC.

quartan Occurring every fourth day, counting inclusively, or every 72 hours. [AHD]

quartern One fourth of something, especially of some weights and measures. [AHD]

quarter-inch jack Same as 1/4" TRS or 1/4" TS, see connectors.

quarter-note Music. A note having one-fourth the time value of a whole note.[AHD] In most popular music, the quarter-note is the value equal to one beat. Also called crotchet (chiefly British).

quarter-track stereo Recording. An analog recording head arrangement that allows recording two tracks in one direction and another two tracks in the opposite direction. The name comes from each track and guard band using one quarter of the tape width.

quartet Mathematics of computing. 1. A group of four adjacent digits operated upon as a unit. 2. A byte composed of four bits, i.e., a nibble. Music. 1. A composition for four voices or four instruments. 2. A group of four singers or four instrumentalists. [AHD]

quartic Mathematics. Of or relating to the fourth degree. [AHD]

quartile Statistics. The value of the boundary at the 25th, 50th, or 75th percentiles of a frequency distribution divided into four parts, each containing a quarter of the population. [AHD]

quartz crystals Electronics. A small crystal of quartz accurately cut along certain axes so that it can be vibrated at a particular frequency, used for its piezoelectric properties to produce an electric signal of constant known frequency. [AHD] See piezo.

quasi- To some degree; in some manner: quasi-stellar object. [AHD]

quasi-balanced line See floating unbalanced line.

quasi-parametric See parametric equalizer.

quasi-peak detector Electronics. A detector having specified electrical time constants that, when regularly repeated pulses of constant amplitude are applied to it, delivers an output voltage that is a fraction of the peak value of the pulses, the fraction increasing toward unity as the pulse repetition rate is increased. [IEEE] In other words, a peak detector with a long time constant.

quaternary The word that comes after primary, secondary, tertiary.

quatrain A stanza or poem of four lines. [AHD]

quatro (also seen as cuatro) Musical Instrument. A stringed Latin American instrument found in the guitar family.

quattuordecillion 1. The cardinal number: 1045. 2. Chiefly British The cardinal number equal to 1084. [AHD]

qubits See quantum dot above.

qubyte A sequence of eight quantum bits operated on as a unit by a computer. [AHD]

Queen, Daniel (1934-2002) Long-time Standards Manager for the AES, Daniel had a full and productive audio career including his successful consulting company, Daniel Queen Associates, specializing in electroacoustics, architectural acoustics, and noise control. He joined the AES in 1962 and became a fellow in 1970.

quena also called a kena Musical Instrument. A shepard's pipe, or flute) without a mouthpiece. [Note: a large quena is called a quenacho.]

queueing The only eight letter English word with five vowels in a row.

quidnunc A nosy person; a busybody. [AHD]

quiescent Being quiet, still, or at rest; inactive. [AHD]

quiescent noise Another name for a product's residual noise or noise floor.

quietest place Microsoft Corporation's anechoic chamber; certified by Guinness World Record organization. Record formally held by Orfield Laboratories in Minneapolis.

quieting sensitivity FM Radio. (Also called IHF Sensitivity.) In simple terms it is the minimum input signal required to provide a distortion-free listenable output signal. In technical terms, it is "the minimum unmodulated signal input for which the output signal-to-noise ratio does not exceed a specified limit, under specified conditions." [IEEE] This test was standardized in 1958 by the IHF (Institute of High Fidelity) to mean the unmodulated carrier amplitude measured in microvolts (rms) required for a specific dB reduction in output noise over the output noise present with no-signal. A typical specification might read: 0.5 microvolts for 20-dB quieting. Also measured in femtowatts (dBf).

quinary The word that comes after primary, secondary, tertiary, quaternary.

quinate Arranged in groups of five.

Quinnipiac (pronounced KWIN-uh-pe-ack) A private, coeducational, nonsectarian university located in Hamden, CT, featuring a fully digital high-definition broadcast studio.

quint Music. Name for an interval of a fifth.

quintal A unit of mass in the metric system equal to 100 kilograms. [AHD]

quintephone Musical Instruments. A musical instrument that generates sound "informatically," i.e., using information science and technology. For example, synthesizers are a subset of quintephones.

quintet Music. 1. A composition for five voices or five instruments. 2. A group of five singers or five instrumentalists.

quintessence In ancient and medieval philosophy, the fifth and highest essence after the four elements of earth, air, fire, and water, thought to be the substance of the heavenly bodies and latent in all things. [AHD]

quinticlave Musical Instrument. A French brass instrument created in the 19th century by Jean Hilaire Asté. It is the alto size of the ophicleide family.

quinton Musical Instrument. A 17th-centruy treble viol. Also, an 18th-century five-stringed hybrid between the viol and violin families. [OED]

quintophonic sound (also seen as quintaphonic sound) The name of the 5-channel discrete surround system developed by John Mosely for The Who's rock opera, Tommy, production. The forerunner of 5.1 surround systems.

quire A set of 25 sheets of paper of the same size and stock; 1/20 of a ream. [Originally 24 sheets, but now 25.]

Quirini, Klaus See: discotheque

quitiplas Musical Instrument. A Venezuelan bamboo instrument.

quodlibet Music. A usually humorous medley. [AHD]

quother Speech. To talk in a low and confidential tone. [Kacirk]

quotient Mathematics. The number obtained by dividing one quantity by another. In 45 ÷ 3 = 15, 15 is the quotient. [AHD]

QWERTY Nickname for the computer (or typewriter) keyboard derived from the left side, top row of letter keys.

AES - Audio Engineering Society