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Recording Studio Glossary

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——— U ———

U Measurements
U Measurements

U – a unit of height for a piece of equipment in a rack. A 1U device is 1.75 inches high, a 2U is 3.5 inches, and a 3U is 5.25 inches. See chart at right.

u – a prefix sometimes used for micro-, meaning one millionth. The correct symbol is μ (the Greek letter mu), but since typewriters and keyboards do not have a μ, a lower-case u is commonly used. For example, you are likely to encounter uF for microfarad, when the correct form is μF.

U 47 – refers to the Neumann U 47 microphone.

U 67 – refers to the Neumann U 67 microphone.

U 87 – refers to the Neumann U 87 microphone.

UAUniversal Audio.

UA 1176 – see Universal Audio 1176.

UA 175 – see Universal Audio 175 and 176.

UA 176 – see Universal Audio 175 and 176.

UAC1 – USB Audio Class 1.0. See USB Audio Class.

UAC2 – USB Audio Class 2.0. See USB Audio Class.

U-Boat™ – trademark of Auralex for proprietary U-shaped channels made of a special rubber compound used to support framing members of a structure to isolate and decouple them from the surrounding structure.

UDF – Universal Disk Format. An open, vendor-neutral file system developed and maintained by the Optical Storage Technology Association (OSTA) for the storage of computer data on a wide range of media, especially recordable optical disc technologies.

UDMAUltra Direct Memory Access.

UHD – see ultra-high-definition television.

UHD-1 – see ultra-high-definition television.

UHDTVUltra-High-Definition Television.

UHF – Ultra High Frequency. The portion of the radio frequency spectrum from about 300 MHz to 3 GHz. The permissable ranges for wireless microphone use (subject to change) is 470 MHz to 608 MHz, 614 to 616 MHz, and 653 to 663 MHz (US), 470 MHz to 854 MHz (UK), and similar ranges in other countries. See also VHF, 2.4 GHz band, 700 MHz band, and the radio frequency chart.

UHJ – Universal HJ. A method developed as a part of Ambisonics for encoding surround sound into mono- and stereo-compatible media. The H and J are simply letter designations that do not stand for anything. Also known as C-Format.

UIUser Interface.

ULUnderwriters Laboratories.

uke – abbreviation for ukulele.

ukulele – a musical instrument, belonging to the lute family, which similar to a small guitar, but having only four strings, usually made of steel or nylon. The ukulele originated in the 1880s as a Hawaiian adaptation of the Portuguese machete, which was introduced to Hawaii by Portuguese immigrants. Ukuleles commonly come in four sizes: soprano (20"), concert (23"), tenor (26"), and baritone (30"). Sometimes abbreviated as uke.


u-law algorithm – (μ-law algorithm) a companding algorithm, primarily used in 8-bit PCM digital audio signals. Companding algorithms reduce the dynamic range of an audio signal, but at an increased signal-to-noise ratio (SNR). Sometimes written as mu-law algorithm. See also au.

ULF – Ultra Low Frequency. The portion of the radio frequency spectrum from about 300 Hz to 3000 Hz. See the radio frequency chart.

ultra direct memory access (UDMA) – an improved version of direct memory access (DMA) with faster transfer rates than DMA. UDMA was the fastest method for transferring data between a computer and ATA device until Serial ATA (SATA) was developed. (ATA stands for AT Attachment, which avoids the name of IBM's trademark Advanced Technology.) There are eight different UDMA modes, with transfer rates from 16.7 to 167 MB/s.

ultraharmonicfrequencies with fractional multipliers of the fundamental frequency, such as 1.5 or 2.5 times the fundamental frequency, in contrast to the whole number multipliers of harmonic frequencies.

ultra HD – see ultra-high-definition television.

ultra-high-definition television (UHDTV) – a television system with higher resolution and other enhancements over high-defintion television (HDTV). Originally proposed by NHK Science & Technology Research Laboratories, the specifications were later defined and approved by the ITU. Two resolutions are considered to be UHDTV, (a) 4K UHDTV (2160p), which is 3840 pixels by 2160 pixels, with four times as many pixels as 1080p HDTV and (b) 8K UHDTV (4320p),which is 7680 pixels by 4320 pixels, which is sixteen times as many pixels and four times the resolution of 1080p. In 2016, the UHD Alliance, an industry consortium of content creators, distributors, and hardware manufacturers, announced its spefications for Ultra HD Premium, defining its requiremnets for resolution, bit depth, color gamut, and high dynamic range (HDR) for products that will carry the Ultra HD Premium logo. Also known as Ultra HD television, Ultra HD, UHDTV, UHD, UHD-1, and Super Hi-Vision.

ultrasonicfrequencies above the normal range of human hearing, typically greater than 20 kHz. See also hypersonic.

ultrasound – sound at frequencies above the range of human hearing (ultrasonic), especially as used in medicine for diagnostic or therapeutic purposes, such as monitoring the progress of developing fetuses.

U-Matic – an analog recording videocassette format using ¾-inch wide magnetic tape introduced by Sony in 1971, one of the first video formats using a cassette, as opposed to the open-reel formats common at the time. In the 1980s, the U-matic began to be used for storage of digital audio data for creating compact discs. The Sony PCM-1600 adaptor allowed a U-matic recorder to store digital audio using PCM. Later the PCM-1610 and 1630 units were used with U-matic cassettes.

umpo – short for up tempo. To increase the tempo of a song. Opposite of dempo.

unarchive – see enable.

unbalanced – refers to inputs, outputs, equipment, and other devices that are connected using unbalanced lines.

unbalanced cable – see unbalanced line.

unbalanced input – an input where the signal consists of the difference in voltage between one lead and ground with the other lead being the same potential as the circuit ground. Unbalanced inputs do not afford as much rejection of external noise as a balanced input.

unbalanced line – a line in which the two conductors are at different potentials with respect to ground, and in which one conductor carries a signal and acts as a shield in contrast to a balanced line where both conductors are shielded.

unbalanced output – an output where the signal consists of the difference in voltage between one lead and ground with the other lead being the same potential as the circuit ground. Unbalanced outputs do not afford as much rejection of external noise as a balanced output.

uncompressed – a file, stream, or signal that has not been data compressed. Not to be confused with decompression, which is the method to restore a compressed file.

uncolored – an audio signal that has not been distorted (colored) in some way. See also transparent.

undersampling – using too low of a sampling rate in analog-to-digital conversion, the cause of aliasing.

Underwriters Laboratories (UL) – a safety consulting and certification company supported by the insurance industry, whose purpose is to ensure fire and hazard safety of electrical appliances and equipment. A device that is tested and approved by UL can display the UL logo, UL surrounded by a circle.

unfocused – a descriptive term for a diffuse sound without directionality, seeming to come from no particular direction. The opposite of focused.

UNICUnion Intenationale des Cinémas.

unidirectional microphone – a microphone with a pickup pattern that has greater sensitivity to sounds coming from the front (on-axis). There are five major unidirectional patterns: (1) cardioid, (2) subcardioid, (3) supercardioid, (4) hypercardioid, and (5) lobar (shotgun). See also directional microphone and polar pattern.

Uniform Resource Locator (URL) – a reference used to locate and retrieve documents and other resources on the internet. URLs are used with several protocols including Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), and email. The URL for a given web page is usually displayed above the page in most web browsers. A typical URL has the form http://www.webpage.com/index.html, where http indicates the protocol, www.webpage.com indicates the hostname, and index.html is the file name. Informally known as a web address.

Union Intenationale des Cinémas (UNIC) – a trade association located in Brussels that represents movie exhibitors and their national associations in Europe to promote the social, cultural, and economic value of cinemas in Europe and around the world.

unison – (1) Two or more performers, instruments, or sound sources sounding the same tones simultaneously with the same frequency or pitch. Compare with harmony. (2) See perfect unison.

Unisys Corporation – an information technology company based in Blue Bell, Pennsylvania, that provides computer services, software, and technology. The company formed in 1984 with the merger of Burroughs Corporation and Sperry Corporation. Burroughs began in 1886 as the American Arithmometer Company. The Sperry Gyroscope Company was founded in 1910 and later merged with the Eckert-Mauchly Computer Corporation, which had developed the world's first commercial digital computers, the BINAC, and the UNIVAC.

United Recording Electronics Industries – see UREI.

unit magnetic pole – a unit of magnetic pole strength equal to the strength of a magnetic pole that repels an identical pole at a distance of one centimeter with a force of one dyne. Also called unit pole.

unit pole – see unit magnetic pole.

unity gain – (1) Having no effect on the level of an audio signal; neither increasing nor decreasing the signal strength of the incoming signal. (2) The setting on a mixermixer or console where there is no increase or decrease in signal strength, usually indicated as 0 dB.

Universal Audio – a company headquartered in Scotts Valley, California, that designs and manufactures audio signal processing hardware and software for the professional recording studio, live sound, and broadcasting. The company began in 1946 when Bill Putnam, Sr. founded Universal Recording Corporation in Evanston, Illinois, to research new recording techniques and specialized recording equipment, with the design and manufacturing being handled by Putnam's other business, Universal Audio. Putnam moved his companies to Chicago in 1947, where he began recording a string of hits. In 1957, Putnam sold his interest in Universal Recording and started United Recording Corporation in Hollywood, California. Universal Audio moved upstairs from the studio changing its name to United Recording Electronics Industries (UREI). UREI had acquired the patent rights for the Teletronix LA-2A Leveling Amplifier from Babcock Electronics. UREI also had acquired National Intertel, which became the Teletronix division. United Recording later merged with Western Recorders to become United Western. In 1985, Putnam sold both companies and left the business. JBL picked up the UREI name and service contracts, and began using the brand JBL-UREI. In 2005, Soundcraft, another division of Harman, began offering products as REI-by-Soundcraft. In 1999, Universal Audio was re-established by brothers Jim Putnam and Bill Putnam, Jr., who offered classic analog recording equipment designed by their father and his colleagues.

Universal Audio 175 and 176 Limiting Amplifiers – two limiters introduced by UREI in 1961. The 175 was one of the first commercial products introduced by UREI. The 176 was released shortly after the 175. They were a variable-mu design. The 175 had a fixed ratio of 12:1, but the 176 had selectable ratios of 2:1, 4:1, 8:1 and 12:1. They were the predecessor to the UA 1176. The 175 and 176 are considered by some to be the best compressors ever made, but they are hard to find in the vintage marketplace. Previously known as UREI 175 and 176.

Universal Audio 1176 – a compressor (peak limiter) designed by Bill Putnam and introduced by UREI in 1968. It was the first true peak limiter with all solid-state circuitry. In 1970, low-noise circuits were added to reduce distortion and LN was affixed to the model number. It was re-issued by Universal Audio in 2000. The 1176LN was inducted into the TECnology Hall of Fame in 2008. Previously known as UREI 1176. See also all-button mode.

Universal Music Group (UMG) – a music company headquartered in Santa Monica, California, which is a subsidiary of the French media conglomerate Vivendi. UMG also owns Universal Music Publishing Group. UMG began as the American branch of Decca Records in 1934, but was spun off in 1939. In 1962 it merged with MCA, becoming the MCA Music Entertainment Group. It was renamed Universal Music Group in 1996. In 1998 the then owner Seagram purchased PolyGram and merged it into the Universal Music Group. PolyGram included Deutsche Grammophon which began as Berliner Gramophone. When General Electric acquired Universal Studios in 2004, Universal Music Group came under separate management from the film studio for the second time. In 2006 UMG came under control of Vivendi which later purchased BMG and EMI.

Universal Recording Corporation – see Universal Audio.

unmute track with CPU-saving preference selected – see enable.

unshadowed ear – the ear on the human head facing or turned toward a sound source. The opposite of shadowed ear. See also head shadow and zone of silence.

update mode – the operating mode in console automation in which previously written automation data can be changed by the engineer beginning at a defined point in the take with the new data being stored for future use.

up-front – a descriptive term for a sound that is more prominent or sounding closer to the listener than other sounds.

upload – (1) To transfer data from a smaller to a larger computer (often to the internet), from a nearby to a distant computer, or from another device to a computer. (2) Data that has been transferred in such a manner. (3) The process of transferring such data. The opposite of download.

upper bass – one of four subdivisions into which bass is sometimes divided, covering the range of 160 Hz to 350 Hz. The other three subdivisions are deep bass (40 Hz to 80 Hz), low bass (40 Hz to 80 Hz), and mid bass (80 to 160 Hz), although these ranges vary from source to source. See also audio spectrum.

upper bout – see bout.

upper cutoff frequency – see cutoff frequency.

upper leading tone – see leading tone.

upper midrange – the portion of the audio spectrum from about 2.5 kHZ to 5 kHz. See also midrange.

upper sideband (USB) – see sideband.

upper tomstom-tom drums that are mounted to a rack over the kick drum. Also called rack toms.

Upright Piano
Upright Piano

upright bass – see double bass.

upright piano – a piano that has the soundboard and strings mounted vertically in a rectangular case with the keyboard at a right angle to the case.

upsample – to increase the sample rate and/or bit depth of an audio file. Upsampling does not increase the audio quality of the file.

upward expansion – see expansion.

UREI – United Recording Electronics Industries. The manufacturing wing of Universal Audio from 1957 to 1985.

UREI 175 – see Universal Audio 175 and 176.

UREI 176 – see Universal Audio 175 and 176.

UREI 1176 – see Universal Audio 1176.

USB – (1) Universal Serial Bus. An external serial bus interface standard for connecting peripheral devices to a computer. USB comes in several versions (which generally refers to the speed and functionality) and types (which refers to the physical shape and the wiring of the ports and plugs). Currently there are three versions: USB 1.0, USB 2.0, and USB 3.0. USB is one of the main methods of connecting audio interfaces with computers, the others being FireWire and Thunderbolt. (2) Upper SideBand. See sideband.

USB 1.0 – USB 1.0 and 1.1, the first commercial versions of USB supports data transfers up to 1.5 Mbps for low-speed devices and up to 12 Mbps for full-speed devices.

USB 2.0 – the second major version of USB, supports data transfers up to 480 Mbps for high-speed devices.

USB 3.0 – the third major version of USB, has a new transfer mode called SuperSpeed (SS) with data transfer rates up to 5 Gbps (625 MBps). USB 3.0 cables can be distinguished from USB 2.0 cables by either the blue color of the ports or the initials SS on the plugs. An updated standard USB 3.1 (called SuperSpeed+), released in July 2013, provides transfer rates up to 10 Gbps (1.25 GBps), which is comparable to the first version of Thunderbolt.

USB Audio Class – specifications for transmitting digital audio using the USB serial bus. The first version USB Audio Class 1.0 (UAC1) was released in 2006. Version 2.0 (UAC2) updated the specifications and provided for handling higher resolution audio and incorporated USB 3.0.

USB bus power – power that is carried over USB cables that eliminates the need for a separate power supply for connected peripherals.

USB client – the device that receives communications on a USB bus. By definition, a computer is alway a USB host, and most peripherals, such as printers and audio interfaces, are USB clients. A tablet can be either, being a host when attached to peripherals and a client when attached to a computer.

USB Connectors
USB Connectors

USB connectors (types) – There are several types of USB connectors. The Type A connector (officially called a Standard A connector) is wide and flat in appearance, and plugs into Type A ports found on most USB host devices, such as computers and USB power adapters. Type A plugs are found on one end of most USB cables and are integrated into smaller devices such as USB thumb drives. The USB Type B connector (officially called a Standard B connector) has a hexagonal-shaped plug, and are found on many USB peripherals, such as printers, keyboards, external hard drives, and audio interfaces. Type A and B connectors used with USB 1.0 and USB 2.0 devices have four pins, while USB 3.0 uses a 9-pin format. Although USB 1.0 and USB 2.0 Type A and B connections are compatible with USB 3.0 connections, you cannot plug USB 3.0 connectors into USB 1.0 or USB 2.0 connections. The Type-C connector (officially called a Standard C connector) is about the same size as that of the Micro-B USB (see below). Both ends of a Type-C cable are the same, and can be plugged in in either orientation so that you do not need to worry about being upside down. It is often called USB-C. There is also a Powered B connection that has 11 pins, with the exta two conductors used to carry power. The USB Micro Type A connector is a compact version of the USB Type A connector utilizing a 5-pin design. The USB Mini B connector is a compact version of the Type B connector and is used on many personal electronic devices, such as smart phones, digital cameras, and even some pro audio gear. The USB Mini B connector is a 5-pin connection and is much smaller than the USB Type B connector. The USB Micro Type A connector is also a 5-pin design and is smaller than the USB Mini B connector. USB 2.0 uses Mini B connectors, but USB 3.0 does not, using only Micro connectors.

USB dongle – see dongle.

USB Flash Frive
USB Flash Frive

USB drive – see USB flash drive.

USB flash drive – a small, portable flash memory storage device that plugs into a standard USB port. It functions as a portable hard drive, but it is more convenient because it can be carried in a pocket and it is more durable because it contains no moving parts. Also called a thumb drive, jump drive, pen drive, key drive, token, USB stick, or USB drive.

USB host – the device that initiates communication on a USB bus. By definition, a computer is alway a USB host, and most peripherals, such as printers and audio interfaces, are USB clients. A tablet can be either, being a host when attached to peripherals and a client when attached to a computer.

USB-IF – Universal Serial Bus Implementers' Forum. A non-profit organization formed in 1995 by a group of companies that developed USB, including Apple Computer, Hewlett-Packard, NEC, Microsoft, and Intel, to promote and support the Universal Serial Bus. The USB-IF hosts the USB.org website, sponsors compliance workshops, provides educational and marketing materials, and holds developer conferences, in order to promote USB technology, develop USB peripherals, and the testing of products for compliance with the USB specification.

USB microphone – a high-quality digital microphone that can plug directly into a USB port on a computer, bypassing the computer's sound card.

USB Micro Type A Connection – see USB connectors.

USB Micro Type B Connection – see USB connectors.

USB Mini B Connection – see USB connectors.

USB-OTG – Universal Serial Bus-On The Go. An extension of the USB 2.0 specifications to enable Android devices to serve as a host for peripherals, such as flash drives, mouses, and audio interfaces.

USB Port – a type of jack found on computers and other device that carries information using USB.

USB Standard A Connection – see USB connectors.

USB Standard B Connection – see USB connectors.

USB Standard C Connection – see USB connectors.

USB stick – (1) Another name for a USB flash drive. (2) Sometimes used as a term for a dongle.

USB thumb drive – see USB flash drive.

USB types – see USB connectors.

USB Type A Connection – see USB connectors.

USB Type B Connection – see USB connectors.

USB Type C Connection – see USB connectors.

USB versions – see USB.

US Copyright Act – the basic framework for current copyright law in the US, which is contained in the Copyright Act of 1976 and subsequent amendments. The 1976 Act was a comprehensive revision of previous copyright laws. The Copyright Act grants five rights to a copyright owner plus a sixth right added by amendment in 1995: (1) the right to reproduce the work into copies and phonorecords, (2) the right to create derivative works of the original work, (3) the right to distribute copies and phonorecords of the work to the public by sale, lease, or rental, (4) the right to perform the work publicly (if the work is a literary, musical, dramatic, choreographic, pantomime, motion picture, or other audiovisual work), (5) the right to display the work publicly (if the work is a literary, musical, dramatic, choreographic, pantomime, pictorial, graphic, sculptural, motion picture, or other audiovisual work), and (6) the right to transmit a sound recording by means of digital audio. These rights are specifically limited by fair use and several other specific limitations as set forth in the Act. The Act spells out the basics of fair use, a doctrine originating in common law and US law that permits limited use of copyright-protected material without having to obtain permission from the copyright holder. Fair use is one of the limitations to copyright intended to balance the interests of copyright holders with the public interest.

US customary units – the system of weights and measures in use in the United States, the only country not on a metric system. (See SI.) Both imperial units and US customary units were derived from earlier English units, and they are closely related, but there are a number of differences between two systems.

user interface (UI) – a set of controls, input devices, commands, or menus through which a user communicates with a device or software program.

UTP – Unshielded Twisted Pair. See twisted pair.

UV-22 – a patented process by Apogee Electronics for maximizing the dynamic range of digital audio by encoding inaudible bias into the digital data at around 22 kHz, which provides for resolutions equivalent to 20 bits on the standard 16-bit digital audio format.

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Note: We believe this is the largest dictionary (glossary) of terms specific to usage within the recording industry that is currently available on the internet, with more than 7,800 entries, nearly 600 illustrations, and dozens of tables. Some of the terms have different or additional meanings in other situations, especially within the electronic, automotive, scientific, and computer industries. Of necessity there are obvious overlaps into other fields such as music, electronics, and computers, but such excursions are limited to information deemed pertinent to the knowledge required to operate and/or participate effectively in the workings of a recording studio. Also included are terms related to sound reinforcement (live performances) including wireless microphone technology because a working knowledge of that terminology is necessary for recording at live performance venues. Because recording studios also record audio for video and motion pictures (films), some terminology from those fields is included. Some scientific terms are included because they help explain studio terminology. For example, electromagnetism explains how microphones, loudspeakers, and guitar pickups work. Knowledge of radio waves and the radio frequency spectrum is needed to explain wireless devices. Any trademarks or trade names mentioned belong to their respective owners. The information contained in this dictionary is believed to be accurate at the time of publication. This information is subject to change without notice. The information was obtained from and cross-checked with a variety of sources that are believed to be reliable. However, Los Senderos Studio, LLC does not guarantee the accuracy or completeness of the information contained herein. Please contact us to report any errors, omissions, discrepancies, or broken links. Los Senderos Studio shall not be responsible for any consequences or damages arising out of the use of this information. Nothing in this glossary should be interpreted as legal advice. For a glossary providing information on legal and business matters for musicians, we suggest you consult Musicians Business Dictionary.

A note on alphabetical order: The terms in this glossary are alphabetical without regard to spaces and punctuation. For example, AM Radio follows amplitude. While this may seem to be at odds with other conventions, it eliminates confusion with words such as pickup, which is sometimes written as pick up or pick-up. The entries on the number page (0-9) are listed in increasing value within each digit. For example, all of the entries beginning with 1 are listed before those starting with 2. For Greek letters (α-ω), the entries are in Greek alphabetical order.