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Music Technology & Home Recording Glossary U-Z

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Ultrasonic: - Sound frequencies which are above the highest frequency of human hearing (20 kHz). See also Infrasonic.

UNBALANCED: A 2-wire electrical signal connection where the inner or hot or +ve (positive) conductor is usually surrounded by the cold or -ve (negative) conductor, which forms a screen against electrical interference.

Undo: Cancels the results of the last operation.

Unidirectional: - A microphone response / pickup pattern which is very sensitive to sounds which are produced in front of the microphone, but very Insensitive to sounds which are produced behind the microphone. (see also Polar Pattern)

UNISON: To play the same melody using two or more different instruments or voices.

Units shipped: The quantity of product delivered by a recording manufacturer to retailers, record clubs, and direct and special markets, minus any returns for credit on unsold product.

USB: (Universal Serial Bus) is a "plug-and-play" interface between a computer and add-on devices such as audio devices, joysticks, keyboards, scanners, and printers. With USB, a new device can be added to your computer without having to add an adapter card or even having to reboot your computer. USB supports a data speed of 12 megabits per second and a single USB port can be used to connect up to 127 peripheral devices. It is best to use self-powered USB hubs and to plug devices into the back of your computer and not the keyboard for optimum reliability. USB 2: Also referred to as Hi-Speed USB, USB 2.0 is an external bus that supports data rates up to 480Mbps. USB 2.0 is a revision of USB 1.1. USB 2.0 is fully compatible with USB 1.1 and uses the same cables and connectors.

VALVE: Vacuum tube amplification component, also known as a tube.

variable bit rate (VBR) - encoding process where the codec makes the choice for how many bits are used on each segment of music. More complex segments get more bits. VBR was created with the goal of efficient use of file sizes.

Variable-Rate Converter: - Digital recording developed originally by the "Kinetix" corporation where the sampling rate "hovers" in a random fashion between 44.1 and 48 kHz. This is done primarily in order to keep sampling errors spread over a wide range of frequencies (when using a fixed rate they may build up around certain frequencies creating noticeable distortion). When spread in this way, they are mostly inaudible, with a perceived improvement in sound quality. However, this system, despite it's advantages, may have problems interfacing with other systems which utilize a fixed sampling rate.

VCA (Voltage Controlled Amplifier): - Acronym of Voltage Controlled Amplifier. A device which responds to a control input voltage (usually @ 0-5 Volts DC). As the input voltage increases, so the level of signal decreases by a proportionate amount. Used extensively in Arturia's software synth Moog, this is an amplifier that will change the gain depending upon the level of control voltage sent to it.

VCD - a Video CD is a compact disc which stores video and audio compressed using MPEG-1 file format technology. Movies are generally compressed to around 352x240 pixels (NTSC) resulting in about 1 GB of data, which spans over two CDs. While they aren't common in the USA, VCDs are more common in other countries where many popular electronics companies sell dedicated VCD players. DVD technology surpasses the quality of VCD technology, mostly due to the increased storage capacity of DVD media.

VCF (Voltage Controlled Filter): - Works along the same principles as a VCA (see above), only with a VCF, it is the roll off frequency of a filter which is affected by changes in control input voltage. A filter whose cutoff frequency or resonant frequency is determined by a control voltage.

VCO - see Voltage-Controlled Oscillator. Oscillator whose output frequency is controlled by variations in Voltage.

Vector Architecture: Used in computer programming, vector architecture allows the simultaneous processing of many data items in parallel. Velocity: The velocity value determines how hard a note is pressed on the keyboard controller. A velocity value can be set either from the controller keyboard or from software, before or after the data is entered.

VELOCITY - a measure of the speed with which a key on a controller is pressed. Used to determine volume characteristics of note.

Velocity (Audio / Acoustics): - The speed at which sound moves through a medium. This depends upon a variety of factors including altitude, temperature and humidity. Allowing for slight variations owing to these factors it is usually between 330 and 350 metres per second. The reference usually used is that in air with a relative humidity of @30% (quite dry) at 0 degrees Centigrade, and at Sea Level (0 feet), Sound will travel through air at a velocity of @ 331.4 metres per second. In your house, at a temperature of @ 20/25 degrees C, it will probably be a little faster.

Velocity (Music & MIDI): - Denotes the speed or force with which a note has been struck. In MIDI , the "Velocity" of a note is a value between 1 and 127. The higher the value, the higher the force that has been used.

Velocity Sensitivity: A keyboard which can respond to the speed at which a key is depressed; this corresponds to the dynamics with which the player plays the keyboard. Velocity is an important function as it helps translate the performer's expression to the music. Velocity can be routed to many destinations on the Emulator III and is also translated over the MIDI line.

Vibrato: A cyclic change in pitch, usually in the range of 7 to 14 Hz. Pitch modulation using an LFO to modulate a VCO.

Virtual Tracks: Tracks which are played back by MIDI modules in real time without being recorded onto multi-track tape. Reasons for using virtual tracks would be to not use tape, or for additional sounds on when there are no open tracks left on the tape.

Vocoder - an audio effect that produces "robotic" sounding results when processing vocal input. It uses an algorithm called ring modulation to produce the effect. Examples can be found in some disco and modern music, such as the Beastie Boys' "Intergalactic". A digital signal processor that applies a filter on a sound based on the frequency characteristics of a second sound. By taking the spectral content of a human voice and imposing it on a musical instrument, talking instrument effects can be created. There are plug-ins available with this effect, such as Native Instruments Vokator.

VOICE: The capacity of a synthesizer to play a single musical note. An instrument capable of playing 16 simultaneous notes is said to be a 16-voice instrument.

Volatile Memory: Memory which loses its data when power is removed. The RAM memory in the Emulator II is volatile, the data on the hard disk is non-volatile.

Volt: - A volt (after the physicist, Count Allesandro Volta) is the amount of elecromotive force required to make one ampere of current flow through one ohm of resistance.

Voltage Pedal: A pedal which outputs a control voltage which is dependant on its position.

Voltage: - Voltage is what is known as the "potential difference" between two points, in electronics meaning the two points between which a flow of electrical current can be carried. It is this potential difference that helps to create Electromotive Force (EMF) that can move electrons, or other charge carriers between two points. It's unit of measurement is the Volt (above).

Voltage-Controlled Amplifier - an audio signal amplifier whose output is controlled by voltage (instead of a potentiometer). VCAs can be used to alter the amplitude of a signal output from a Voltage-Controlled Oscillator.

Voltage-Controlled Filter - a filter whose cutoff frequency and resonant frequency is adjusted using a control voltage. VCFs are used to filter the audio signals generated by VCOs in an analog synthesizer in order to create more interesting and textured sounds.

Voltage-Controlled Oscillator - an analog circuit that generates a electrical waveform, such as a Sine, Saw or Square wave where the pitch is determined by a control voltage. VCOs are used by older analog synthesizers to generate the base sounds which are then altered by Voltage-Controlled Amplifiers and Voltage-Controlled Filters.

VST Plug-In - a program that uses Steinberg's VST technology to obtain digital audio samples which are then manipulated by applying reverb, compression or some other type of audio signal effect. The output signal may be rendered off-line or generated in real-time while the plug-in's host program performs playback. See Plug-In for more details.

VU Meter: Meter designed to interpret signal levels in roughly the same way as the human ear, which responds more closely to the average levels of sounds rather than to the peak levels. The Volume Unit Meter is designed to visually interpret signal levels in roughly the same way as the human ear, which responds more closely to the average levels of sounds rather than to the peak levels.

WAH PEDAL: Guitar effects device where a bandpass filter is varied in frequency by means of a pedal control.

WARMTH: Subjective term used to describe sound where the bass and low mid frequencies have depth and where the high frequencies are smooth sounding rather than being aggressive or fatiguing. Warm sounding tube equipment may also exhibit some of the aspects of compression.

WATT: Unit of electrical power.

WAV: The computer file extension for a WAV file is ".wav.” his is a PC digital audio file format which is quite large because it is not a compressed format.

Wave: - All sound moves as a wave, and the graphic description of a sound is known as a waveform, its shape determined by the levels (amplitudes) of the Fundamental Frequency, and (unless the wave is a pure Sine Wave) the harmonics which follow.

Waveform Editors: Software that allows waveforms to be manipulated through edits such as cuts, splices, loops, and redraws. Depending upon the sophistication of the software, one can edit extremely detailed amounts of data. Steinberg’s Wavelab is an excellent editor for the PC.

WAVEFORM: A graphic representation of the way in which a sound wave or electrical wave varies with time. A cyclic propagation of energy through a medium at a constant velocity. e. g. sound pressure waves through air, or a diagram of such oscillations. Also refers to the appearance of the oscillating voltage of an audio signal on an oscilloscope. See also Pulse Wave, Ramp Wave, Sine Wave, Square Wave, Triangle Wave

Wavelength The distance between two identical points on a waveform i.e. one cycle of the waveform, or the spatial distance between two identical points of an electromagnetic or sound pressure wave which have the same phase. In high frequency waves, there are more cycles in a given unit of time than there are in low frequency waves, this means they are closer together and consequently the wavelength of a high frequency is shorter than that of a low frequency. The wavelength of an given frequency can be determined by dividing the speed of propagation of the wave by its frequency. For electromagnetic waves this is c/f, where c is the velocity of light and f is frequency, this gives a result in metres. For sound pressure waves it is approximately 334 m/s divided by the frequency in Hz, so that audio frequencies have wavelengths in the range from 16 metres to 1.6 centimetres.

WAVETABLE - a storage location that contains data used to generate waveforms digitally.

Wavetable Synthesis: A method of generating waveforms through lookup tables. Many software synthesizers use wavetable synthesis where these digitized waveforms are organized in a bank or table, accessed through a sequencer.

Wet signal: - signal which has been processed in some way (by reverb, eq, or whatever). Opposite of "dry" signal.

White Noise A signal which contains all possible audio frequencies in equal average amplitudes. Useful for testing equipment. A random signal with an energy distribution that produces the same amount of noise power per Hz.

Wide Field: - see Near Field.

Wind Controller: A controller 'instrument' which is woodwind-like or brass-like in it's fingering. They are blown into and the air stream triggers sounds from a synthesizer or tone module. Many do not have sounds of their own and must be connected (through Midi) to a synthesizer or tone module. They will play whatever sound is called up on the connected synthesizer.

Windows WAVE: This format was created by Microsoft and IBM, and it has unfortunately become a popular standard. It has a plethora of different compression formats, although the Microsoft ADPCM is the most popular.

WMA (.wma) - "Windows Media Audio", Microsofts proprietary audio codec designed to compete with MP3. Claims competitive sound quality at lower bitrates

WMDM - Windows Media Device Manager is a Microsoft software component that enables Windows applications to share and transfer files to and from non-PC devices, such as portable MP3 players, in a standardized way. The use of a common software component enables greater software and hardware compatibility and support.

Woofer [or Sub Woofer]: A speaker that is used for low-frequency reproduction.

WORD CLOCK: The precise and accurate timing of digital audio samples is critical to the correct operation of interconnected digital audio equipment. The 'metronome' that governs sample timing is called the Word Clock (sometimes conjoined to 'Wordclock', or abbreviated to 'Wclk'). However, word clock does more than merely beat time; it also identifies the start and end of each digital word or sample, and which samples belong to the left or right channels. Digital interfaces such as the AES-EBU and S/PDIF embody clock signals within the data stream, but it is often necessary to convey a discrete word clock between equipment as a square wave signal running at the sampling rate. Dedicated word clock inputs and outputs on digital equipment generally use BNC connectors (the kind of terminals commonly used for video).

Word Length: The number of bits per sample that a digital device (such as an A/D converter) uses to convert or store data. The greater the number of bits in a digital sample, the more accurate the digitized description of the instantaneous analog signal value. Also called bit depth, bit rate or bit resolution.

Word: One sample of audio data.

World Intellectual Property Organization Treaties (WIPO): These treaties, negotiated in December 1996 by more than 100 nations at the World Intellectual Property Organization Diplomatic Conference in Geneva, will secure copyright protections in cyberspace and strengthen copyright law in nations around the world. They represent the most important overhaul of international copyright law in the last quarter-century. The treaties bring international copyright standards closer to U.S. law, raising the minimum standards for copyright protection worldwide and making it easier to fight piracy of American products overseas. The only changes in U.S. law required by the treaties involve prohibitions on technologies used to undermine the electronic "locks" protecting copyrighted works online. These prohibitions are included in the Digital Millennium Copyright Act passed this year as the treaties were approved, providing a model for international action and approval of the treaties. Thirty nations must ratify the WIPO treaties for them to take effect.

WTO -The World Trade Organization (WTO): The World Trade Organization is an international body that has jurisdiction over trade disputes involving intellectual property rights agreed to in TRIPS.

Wow and Flutter: - More from the old days of tape machines, turntables etc than the modern, "digital" age. This is when slight variations in the speed of a tape transport, turntable motor etc creates an annoying "wobbly" variation in pitch. Generally, the "wow" part describes the effect created by slower variations in speed over a longer period, whereas "flutter" describes sharper variations over a shorter period of time.

Write Protect: To protect data (either on a disk or in memory) from being written to, although data can still be read.

WRITE: To save data to a digital storage medium, such as a hard drive.

XG: Yamaha's alternative to Roland's GS system for enhancing the General MIDI protocol so as to provide additional banks of patches and further editing facilities.

XLR Connector: - Short for "X-tended Locking Round" A professional standard, three pin balanced connection system, originally developed by the ITT and Cannon corporations. It is a standard connection for microphones, and frequently used for much professional equipment which requires balanced inputs / outputs. Many audio cards, like Aardvark’s Q-10 and Edirol’s USB audio interfaces such as the new UA-1000 have the XLR connection directly on the front panel for ease of use.

Y-Connector: - Where two connectors are fed into one connector of the same type, enabling a signal path to be split into two.

Yellow Book" Standard: - Originally devloped by the Phillips and Sony corporations, and similar to the "Red Book" standard (see above). However it is slightly less strigent, in order to accomodate the CD ROM drives found in most Personal Computers.

Y-Lead: Lead split so that one source can feed two destinations. Y leads may also be used in console insert points in which case a stereo jack plug at one end of the lead id split into two monos at the other.

ZENITH: Parameter of tape head alignment relating to whether or not the head is perpendicular to the tape path, and aligned so as to be in the same plane. - See Azimuth (Alignment).

Zero Crossing Point: - Both sounds and electrical signals are primarily oscillations, and they oscillate around around an equilibrium or axis known as the "zero crossing point", where a negative signal crosses over into being a positive signal, or vice versa. It is also sometimes referred to as the "null point".

Zero Level: - The level of 0dBV. This is NOT the lowest level, but rather, it is (usually) the optimum level for recording and broadcast purposes, getting the best signal to noise ratio without "going into the red", and the distortion that entails.

ZIPPER NOISE: Audible steps that occur when a parameter is being varied in a digital audio processor

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