Music Technology Glossary of Terms

ADAT: A trademark of Alesis Corporation for its modular digital multitrack recording system released in early 1993 and stands for Alesis Digital Audio Tape. It records eight tracks digitally on a standard 1/2" SVHS video cassette and is currently a 20-bit digital format. The ADAT optical connections for transferring the digital data 8-tracks at a time are used in a wide range of products from many manufacturers.

ADAT Lightpipe: A digital interface that allows 8 individual tracks to pass through an optical (Toslink) cable. Lightpipe is used with ADAT machines and is incorporated in numerous soundcards and multiple AD/DA converters. Sonorus STUDI/O is a ADAT Lightpipe soundcard.

Additive Synthesis: A method of synthesis that builds complex waveforms by combining sine waves with independently variable frequencies and amplitudes. Envelope shapers and filters can further process these waveforms. Hammond organs and similar instruments make the most use of simple additive synthesis.

ADSR: Attack, Decay, Sustain, and Release are the four parameters found on a basic synthesizer envelope generator, and they match the physical attributes of naturally occurring sound. An envelope generator is sometimes called a transient generator. The Attack, Decay, and Release parameters are rate or time controls. Sustain is a level. When a key is pressed, the envelope generator will begin to rise to its full level at the rate set by the attack parameter, upon reaching peak level it will begin to fall at the rate set by the decay parameter to the level set by the sustain control. The envelope will remain at the sustain level as long as the key is held down. When a key is released, it will return to zero at the rate set by the release parameter.

Aliasing: Unwanted frequencies produced when harmonic components in the audio signal being sampled by a digital recording device or generated within a digital sound source are above the Nyquist frequency. Aliasing is also sometimes referred to as fold-over. See Nyquist Frequency.

Altivec: A programming tool developed by Motorola, Alivec is a short vector architecture technology that accelerates software. (See vector architecture). BIAS's latest version of Peak implements an altivec-based convolution technology which allows natural reverb impulses to be applied to dry audio signals, giving the impression that a file was actually recorded in a particular environment.

Amplitude: A digital audio file’s sound levels or electrical signal levels. It refers to the height of a waveform—the greater a sound wave's amplitude, the louder it sounds. Most software audio programs allow viewing the amplitude of the waveform for detailed editing.

Analog: An analog audio signal is represented by variations such as voltage speed or frequency and the strength of amplitude or volume of an electrical audio signal. The audio outputs from a computer’s soundcard or synthesizer are typically analog outputs even though the file being played is digital through a D/A converter. See D/A..

Analog Synthesis: Electronic synthesis, electronic oscillators, filters, and envelopes are used to directly create and manipulate sound. It does not involve sampling rate, bit depth, or other digital factors. (Such as older Analog Synthesizers/Keyboards used in the 1970s).

(A/D) Analog to Digital Conversion: An electronic device that converts analog signals from a microphone or line level source into digital signals (digitizing or sampling them) so they can be stored to any number of storage media like hard drives, ADAT, computer ROM chip, or processed in a sampler, digital signal processor or digital recording device.

Audiophile: A person enthusiastic about sound reproduction who is discerning about the quality of the audio.

Auto Accompaniment: This generally refers to software such as PG Music’s Band in a Box that provides a ready-made back-up band.

AUX: An “auxiliary” physical control knob on a mixing console designed to route a portion of the channel or channels signal to the effects or other mix outputs. Edirol’s new audio mixer, the M-100FX has aux bus ports with a stereo return and a mono send.

Bandwidth: A means of specifying the range of frequencies passed by an electronic circuit such as an amplifier, mixer or filter. A system's bandwidth is the total frequency range of the system. (Example 20Hz-20Khz)

Bank: A storage location in a sampler or synthesizer that holds a large number of individual sounds. Typically, any synthesizer that isn’t General MIDI utilizes banks to organize the additional sounds and there can be up to 127 sounds within each bank.

Bank Select Message: A MIDI control change message which instructs a receiving synth to switch to a different bank so that another instrument or sound can be accessed within a sequence.

Bit: Otherwise known as "Binary Digit,” it is a unit of digital information. A bit represents either an "on" of "off" value represented by a “0” or “1.” A bit is 1/8th of a byte.

BNC: Bayonet Nut Connector provides a secure, easy-to-use means of connecting shielded cables to electronic equipment used for high-end video, computer networking and digital audio. Word clock usually uses a BNC connector and is on the Edirol DA-2496, an 8 in, 8 out PCI soundcard.

Bouncing: This is the process of mixing two or more recorded tracks and re-recording (the sum of the original tracks on to another track) these on to another track.

BPM: Beats per minute. (example: a rap song with 130 bpm has more beats per minute than a classical song at 60 bpm)

Breath Controller: This is a controller that converts breath pressure into MIDI data. Although not common, these controllers are synthesized renditions of acoustic woodwind instruments and are especially beneficial when assigning a wind instrument in a sequence.

Bulk Dump: Used with synthesizers, a bulk dump transmits a chunk of data commands known as system-exclusive messages. Generally a synth can send and receive bulk dumps to a sequencer, either software or a stand alone synth.

Buffering: This is a method for temporarily storing or delaying data samples before processing or conversion.

Buss: A common electrical signal path along which signals may travel, a mixer would have several busses carrying the stereo mix, the groups, and the Aux sends.

Byte: A unit of digital value which consists of 8 bits, usually in the number of bytes such as kilobytes, megabytes, and gigabytes.

Capacitance: Property of an electrical component able to store electrostatic charge, like a battery.

Cardioid Microphone/Pattern: A unidirectional microphone with a moderately wide front pickup (131 degrees).

Channel: A channel is a path for passing data or digital audio. In sequencing, each channel is assigned to a single instrument in any particular instant of time and in General MIDI, channel 10 is reserved for a percussion voice. One MIDI port makes 16 MIDI channels available so one song could have 16 different channels/instruments assigned to one MIDI port. Also, audio channels on a soundboard.

Channel Messages: MIDI channel messages refer to data specific to one particular MIDI channel. Data such as note on/off, note number, velocity, program change, pitch bend, after touch, and controller messages are channel messages.

Click track: Metronome pulse provided in software which assists musicians in keeping a consistent tempo.

Clipping: Distortion occurs when an amplifier is driven to play louder than its power supply allows and the result is clipping. This state can cause loudspeaker damage. It is of particular importance with digital audio recording because the clipped waveform contains an excess of high-frequency energy and the sound becomes hard and edgy. With analog linear recording it is standard to record as hot as possible; with digital non-linear recording, recording too hot will result in disastrous clipping.

Codec: A codec (compression/decompression or coder/decoder) is a software component that is used for compressing and decompressing data such as audio (MP3) or video (MPEG). Among others, codecs exist for WMA, QuickTime, Streaming Audio, and RealAudio.

Compression: Compression in audio recording means to reduce the dynamic range of a signal.

Compressor (Limiter): A compressor provides a form of automatic level control. It attenuates high levels, thereby reducing the dynamic range, making it easier to control signals and set appropriate fader levels. By reducing the dynamic range, recording levels can be set higher to improve the signal-to-noise performance. Limiting is an extreme form of compression, where the output signal is sharply attenuated so that it cannot exceed a particular level. There are software compressors available such as are within Cakewalk’s AFX1, and hardware units also can have this effect, such as Edirol’s USB audio interface, the UA-700.

Condenser Microphone: A microphone that generates an electrical signal when sound waves vary the spacing between two charged surfaces, specifically the diaphragm and the backplate.

Control Change Message: A group of MIDI channel messages that are used to alter a sound. Examples of control change messages include volume (#7), pan (#10), modulation wheel (#1), and sustain pedal (#64). Some are continuous controllers and utilize hardware such as sliders, wheels, and sweep foot pedals, while others are on-off switch types such as switches or sustain pedals.

Controllers: Hardware devices that output MIDI and come in a variety of shapes. Although the typical controller is a keyboard, Contour Designs has cool ergonomic palm-fitting controllers: the Shuttle Pro and Space Shuttle.

Crossover (Electronic): An electronic device or circuit that, when inserted between a mixer and amplifier, divides the audio spectrum into individual frequency ranges (low, high, and/or mid) before sending them to specialized amplifier/speaker combinations. In many computer speakers, a crossover routes high-frequency sounds to satellite modules and low frequencies to the bass unit. An advantage of this type of crossover is that it increases efficiency.

Crossover Frequency: The frequency in which the audio signal is divided by a crossover.

Crossover(Passive): An electronic device that, when inserted after the amplifier, divides the audio spectrum into individual frequency ranges (low, high, and/or mid) before sending them to specialized speakers like tweeters and woofers.

Cycle: One complete vibration of a sound source or its electrical equivalent. One cycle per second is 1 Hertz (Hz).

Daisy Chain: A group of devices or modules connected to each other in a series, where the first one connects to the computer, the second one connects to the first and so on. This would include SCSI, USB and FireWire connectivity.

Damping: Damping refers to the ability of an audio component to stop after the signal ends. For example, if a drum is struck with a mallet, the sound will reach a peak level and then decay in a certain amount of time to no sound. An audio component that allows the decay to drag on too long has poor damping and less definition than one wants. An audio component that is over-damped does not allow the initial energy to reach the full peak and cuts the decay short. Boomy or muddy sound is often the result of under-damped systems. Dry or lifeless sound may be the result of an over-damped system.

DAO: Disc at Once; a recordable CD method where the session is recorded in one pass without interruption (the laser does not turn off). This is ideal when sending audio recordings to be mastered or pressed as most mastering and/or duplication facilities machines will fail or error out if it detects that the laser was turned off.

DAT: Abbreviation for “Digital Audio Tape,” it is a digital tape-recording format using a small cassette that provides up to two hours of 16-bit, linear, PCM digital recording at a sampling rate of 32, 44.1 or 48 kHz. A significant advantage that a DAT has over most MiniDisc is that most DAT players will have a digital output, useful when transferring the file to the computer for editing, provided that the soundcard has a digital input. The Edirol UA-1D is the perfect device for this digital transfer with both digital ins and outs.

DAW: Digital Audio Workstation, such as Roland’s VS-2480.

dB (Decibel): A unit used for measuring voltage, current or power. The decibel is often used to measure differences in sound pressure level or relative loudness.

Decoding: This is the process whereby information in a compressed digital audio file is read/expanded so that it can be converted from digital to analog to go to speakers so we can hear. There are software MP3 players that both decode and play MP3 files.

De-Esser: Device for reducing the effect of sibilance or excessive “esses” in vocal signals.

Delay: A common effect in a sampler or synthesizer [or effects] that mimics the time difference between the arrival of a direct sound and its audible first reflection.

Detent: Physical click stop in the center of a control surface such as a pan or EQ cut/boost knob.

Digital: The phrase “digital audio recording” is contrasted with “analog audio recording.” Long-playing phonograph records are analog recordings and they capture information in a continuously-variable form. Digital, in contrast, involves binary numbers--1's and 0's. Digital encoding can “think” only in terms of the binary numbers 1 (on) and 0 (off), therefore a synthesizer produces sounds by performing mathematical manipulations upon a stream of numbers which are then transformed by a digital-to-analog converter to an electrical signal. In analog there is no conversion taking place, but every time you copy or boost there can be added noise or loss of original content with each pass which does not happen with digital.

Digital Audio Extraction: A method of retrieving audio samples from an audio CD in order to create a computer audio file. This is also known as ripping. This can be accomplished at “CD” quality or MP3 quality MP3, being a digital compression format, will take up less space than a “CD” quality file on a computer audio file.

(D/A) Digital to Analog Conversion: The process by which digital data (0’s and 1’s in binary computer language) is reconverted back to an analog (electrical) audio signal. This is how compact disk players play back CDs, and is the same means by which digital synthesizers and samplers play back their sounds through analog outputs such as speakers or headphones.

Dither: This tool is used with high-end audio recording programs and audio converters to improve audio quality. It is a mathematical process where a random noise is added to the least significant bit of a digital word to improve audio fidelity when needed. The ability to dither an audio file is absolutely required for good digital audio recording and audio editors such as Sonic Foundry’s Sound Forge and Steinberg’s Wavelab have excellent dithering capabilities.

Dolby Digital: A five-channel audio system with all processing in the digital domain consisting of left, center, right and left rear, and right rear channels and optional subwoofer. This is also referred to as Dolby Digital 5.1. Unlike Dolby Prologic in which the rear effects channel’s frequency is limited to approx. 100-7000Hz, Dolby Digital rear channels are specified to contain the full 20-20Khz frequency. When an audio file has already been encoded with Dolby Digital, Edirol’s USB audio interface, the UA-3D has the ability to pass through the signal.

Driver: Piece of software that handles communications between the operating system and a hardware peripheral such as a soundcard, printer, MIDI card or scanner.

Dry: When recording audio, this refers to an audio signal which has had no effects added. The best practice is to record dry so one can audition a variety of effects in post production.

DSP Digital Signal Processing: DSP chips are found in sound cards, synthesizers, effects units, playback and speech synthesis, fax machines, modems, cellular phones, high-capacity hard disks and digital TVs. It is possible that the first DSP was used in the Speak & Spell game in the late 1970s from Texas Instruments. Typically, digital signal processing provides reverb or delay effects, loud speaker processing, EQ limiting and compression as well as feedback destroyers. Other audio uses are amplifiers that simulate concert halls and surround-sound effects for music and home theater. See DSP and Merge.

DSP Hardware: DSP hardware frees up a computer’s processing power and speed for other tasks. TC Work’s Powercore is an excellent example of a PCI card which offers DSP processing on the hardware itself—a huge selling feature for this high-end soundcard.

DSP Software: DSP software allows you to clean up or enhance the sound quality while others allow you to apply effects such as distortion or flange. There are many digital audio recording programs with DSP features, as well as plug-ins that are available such as Wave’s Renaissance Max.

Dubbing: Within audio files, this refers to adding further material to an existing recording and is also known as overdubbing. See Overdubbing.

Ducking: Ducking is used to automatically reduce signal levels when the level of a source signal exceeds a specified threshold. Often used for voice-over applications, the level of background music is automatically reduced (made to "duck"), allowing an announcer to be heard clearly.

DVD-A: DVD audio authoring is DVD encoding software. Minnetonka’s discWelder STEEL allows formats supported in the DVD-A specification, including non-encoded, uncompressed surround and or high-resolution stereo (two channels of 24-bit, up to 192 KHz audio), in WAV or AIFF file format. Surround and stereo tracks may be used on the same disc, and a discWelder-burned disc will play on any DVD-A player that supports DVD-R/RW.

Dynamic Microphone: A type of microphone that works on the electric generator principle, where a diaphragm moves a coil of wire within a magnetic field and is typically less sensitive than Condenser Microphones where you need more gain.

Dynamic Range: This refers to the difference between the loudest (maximum output level) and quietest (residual noise floor) sounds produced in an audio system without distortion or clipping. The dynamic range in a digital system is determined by the data resolution, about 6 dB per digital bit. In speech, the range rarely exceeds 40 dB; in music, it is the highest in orchestral works where a broad number of instruments are used, where the range may be as much as 75 dB.

Dynamics: The relative loudness or softness of a piece of music.

Effect: Device for treating an audio signal in order to change it in some creative way. Effects often involve the use of delay circuits and include such treatments as reverb and echo. Software plug-ins can provide these effects and they are also available onboard with USB soundcards such as Edirol’s UA-700 and SD-90.

Electret Microphone: A condenser microphone that uses an electret (electrical-magnet) to hold a permanent electrical charge, enabling it to function in low-voltage.

Enhancer: A device designed to brighten audio material using techniques such as dynamic equalization, phase shifting and harmonic generation.

Envelope: In audio recording software this refers to the way in which the level of a sound or signal varies over time, including alterations in a sound's amplitude, frequency and timbre. In MIDI, an instrument can be altered by manipulating the envelope which contains parameters such as attack, sustain, decay and release. (See ASDR). Using patch editing software the user is able to edit the envelope of a synthesized sound thereby allowing its customization.

Envelope Generator: A device or process in a synthesizer or other sound generator that creates a time varying signal used to control some aspect of the sound.

Equalizer: Device for selectively cutting or boosting selected parts of the audio spectrum; useful in shaping the vocal or instrument for the desired sound like cutting the high end off of a violin.

Event: Because MIDI utilizes commands, most sequencing software has an Event List or an Event Editor where one can scrutinize and change commands such as note on, note off, program change, control change or volume.

Event List: Each MIDI track’s content is shown alphanumerically with information such as note, volume and panning, allowing very detailed editing.

Exciter: A circuit designed to enhance the presence of an audio signal by synthesizing new high frequency harmonics to make it sound more clear, punchy, bright, or loud, without the use of ordinary EQ or gain.

Fade in/out: A feature of most audio editing software that allows the user to apply a gradual amplitude increase or decrease over some segment of the sound.

File Types: There are two MIDI file types and although they sound the same upon playback, they are visually different. Type 0 has all of the information on a single track even though the MIDI file may have been a multiple-channel file; typically these are used in a stand alone MIDI file player. A MIDI File Type 1 contains one or more simultaneous tracks which are better for editing.

Formant: Frequency component or resonance of an instrument or voice sound that doesn't change with the pitch of the note being played or sung. For example, the body resonance of an acoustic guitar remains constant, regardless of the note being played.

FM Synthesizers: These produce sounds by generating a pure sine wave (carrier) and then mixing it with a second waveform (modulator). When the two waveforms are close in frequency, a complex waveform is produced. By controlling both the carrier and the modulator it is possible to create different timbres, or instruments. FM synthesis is hardly used today being replaced by more realistic forms of synthesis, such as wave table synthesis.

Frequency: The rate per second at which an oscillating body vibrates. Usually measured in Hertz (Hz), humans can hear sounds with frequencies in the range of 20 Hz to 20 kHz.

Fundamental Frequency: This is the predominant frequency in a complex waveform and typically provides the sound with its strongest pitch reference. Any sound has a fundamental or basic frequency plus harmonics and partials at a higher frequency.

General MIDI (GM): A standard set of rules within MIDI that allows for cross-instrument compatibility. General MIDI instruments such as many Roland products all use the same memory areas for sound storage and always use MIDI channel 10 for drum parts. General MIDI files provide access to 128 instruments, are capable of playing at least 16 sounds simultaneously and have at least 24-note polyphony.

General MIDI 2 (GM2): An expanded set of parameters for fuller compositions that allow additional controllers, effects and more instruments. MIDI files that are GM2 will be backward compatible to GM, but for these files to be heard utilizing all of the additional accoutrements that GM2 has to offer, they must be played back on a GM2 synth. The Edirol HQ Hyper Canvas is a software synthesizer specifically designed for GM2 MIDI files, as are the Edirol modules, the SD-20, SD-80, and SD-90.

Global Editing: These are MIDI or audio events which affect an entire file or sequence.

Graphic Equalizer: Many audio editing programs such as Cakewalk’s Sonar and Steinberg’s Cubase include this helpful tool; it applies a series of band filters to an audio file, each of which works on a certain range of the spectrum. For example, the frequencies that fall within the range, typically one-third octave, can be boosted or cut.

Harmonics: A frequency that is a whole-number multiple of the fundamental frequency. For example, if the fundamental frequency of a sound is 440Hz, then the first two harmonics are 880Hz and 1,320Hz (1.32kHz). See Overtone.

Harmonic Distortion: The addition of harmonics that was not present in the original signal.

Hertz (Hz): A unit of measurement denoting frequency originally measured as one cycle per second (CPS): 20 Hz = 20 CPS. Kilohertz (kHz) are Hertz measured in multiples of 1,000.

High Pass Filter (HPF): A device which allows higher frequency data to be transmitted, rejecting lower frequencies, as used in Graphic EQ’s. For example, your HPF is set at 100Hz. This means everything below 100Hz to 20 Hz will not be as present in your audio signal. If you had a bass drum mic’d, you would not get any low end thump. See Low Pass Filter.

Imaging: This is an audio listening term and refers to the ability of a speaker to position sounds precisely in space. A good stereo system can provide a stereo image that has width, depth and height. The best imaging systems will define a nearly holographic recreation of the original sound.

Impedance: A measure of the AC (alternating current) resistance to the flow of electrical or acoustic energy. In electronics it is measured in Ohms.

Initialization: Typically used with synthesizers, it is a procedure which places default values or factory settings into some or all parameters. It is especially helpful when clearing out a multitude of previously sent MIDI messages.

Interface: An audio interface such as Echo Audio’s Layla allows the computer to communicate with a microphone or line level device. A MIDI interface such as any Edirol USB MIDI product, allows communication between the computer and a synthesizer or controller keyboard.

Loop: To repeat a sequencer pattern or portion of an audio sample repeatedly. The point to which the program returns, whether the beginning or some other point, is usually definable by the user.

Low-Pass Filter (LPF): Also called a High Cut Filter. A device which allows lower frequency data to be transmitted, rejecting higher frequencies. Most subwoofers have low-pass filters built in and many surround sound decoders have subwoofer outputs that have been low-pass filtered. See High Pass Filter.

Mapping: In sequencing it is the process of identifying patches and keys so that sound files can be played properly. A key map will translate values for MIDI messages so that the correct keys will be played whereas a patch map functions to identify the correct patches or sounds. A typical use would be when a non-General Midi (GM) synth needs to be mapped for a GM file.

Marker: In sequencing and audio software, a marker is used to record a position for easy editing navigation.

Meta Events: The prefix “Meta” often means above or beyond and in computing, a Meta character conveys information about other characters. In MIDI, a Meta event is illustrated by such things as track name, patch name, tempo, time signature, etc. Meta events are contrasted with data streams.

Milli- : An prefix meaning 1/1000.

MIDI: An acronym for the Musical Instrument Digital Interface, a standardized digital “language” that allows electronic musical instruments and computers to communicate with one another.

MIDI Cable: A special wire used to carry MIDI data; it has three shielded conductors connected to five-pin DIN plugs at both ends. It is not a MIDI interface by itself but most interfaces such as the Edirol UM-1S, the UM-550 and the UM-880 need MIDI cables to complete the communication between the computer and MIDI hardware.

MIDI Controller: This is a hardware device that outputs MIDI data such as Edirol’s PCR-30 or PCR-50 keyboards. Other forms of controllers include drum, guitar, or wind controller. Real-time controllers are either continuous controllers (wheels, joysticks, sliders, foot pedals, breath controllers) or switch controllers (footswitches or other on-off devices). Many MIDI controllers do not have sounds but are used specifically to send MIDI data to another device such as a computer or a sound module.

MIDI Implementation Chart: This comprehensive document resides within most synthesizer manuals and describes what MIDI messages, such as note number, velocity, aftertouch, bender, control change, program change, and system exclusive messages are transmitted or recognized by the synthesizer.

MIDI Filter: Many sequencing and digital audio recording programs utilize filters to assist the user with the editing of their data. A filter is especially useful if you are replacing MIDI data such as changing a violin to a viola.

MIDI Messages: The net effect of MIDI is sound: melodies, harmonies, rhythms, but the MIDI message or MIDI event itself is not a sound but a command. MIDI messages transmitted are digital commands and capable of sending about 1,000 events per second.

MIDI Ports: Physical connector through which MIDI data enters or leaves, depending upon which kind of port it is as there are three kinds of MIDI ports: In, Out, and Thru. MIDI data enters an instrument at its MIDI In port (often called a MIDI Input) and leaves the instrument from its MIDI Out port (often called a MIDI Output). The MIDI Thru is a more unique port that sends a copy of the data currently being received at the MIDI In port.

MIDI Sound Generator: For authentic reproduction of acoustical instruments, it uses samples—instrument sounds stored as digitized audio. This is actually another term for synthesizer—converting MIDI events into real audio sound.

MIDI Thru: One of a synthesizer’s three ports (connections): MIDI In, MIDI Out, and MIDI Thru. MIDI In receives information from other equipment; MIDI Out sends information to other equipment. MIDI Thru duplicates the information and sends it to other equipment so a synthesizer can echo messages to other synthesizers. This is particularly useful when daisy chaining MIDI equipment.

MIDI Time Code (MTC): A MIDI system realtime message that assigns a unique address to each moment in time (usually each 120th of a second). Similar to SMPTE time code but transmitted via MIDI ports, it is used mainly for the playback synchronization of MIDI files and digital audio.

MiniDisc: A compact data storage medium designed to store music. MiniDiscs come in two varieties: playback only and recordable. Introduced by Sony in late 1992 and features random access similar to CDs.

Modular Digital Multitrack (MDM): A multitrack digital recorder with (usually) 8 tracks that can be run in synchronization with other machines (of the same type) to attain more tracks. ADAT brand recorders are an example.

Monophonic: Originally, and still, can refer to only one sound source or signal derived from one sound source. For synthesizers this refers to only one note, pitch or voicing, audio or MIDI, being heard at a time.

MP: Multi-processor.

MP3: MP3 stands for MPEG 1, Audio Layer 3. It is an encoding format which takes out all the irrelevant data in a recording and compresses the remaining data. An MP3 file can be 1/12 the size of an original recording taking up far less space on a computer’s hard drive, making it feasible to email the audio file, post on the web, make MP3 CDs and use with personal music players such as Apple’s iPod.

MPEG2: Compared to MP3, MPEG2 provides higher quality music compressed to 70% of its original size and accommodates up to 48 audio channels and sample rates up to 96kHz.

Multi-Sample: The creation of several samples, each covering a limited musical range, the idea being to produce a more natural range of sounds across the range of the instrument being sampled. For example, a piano may need to be sampled every two or three semitones in order to sound convincing.

Multi-Timbral: In sequencing, a multi-timbral sound module can play several parts on different channels simultaneously. A multi-timbral device is one that is prepared to sound like more than one instrument at a time.

Multi-Track: A recording device capable of recording several parallel parts or tracks which may then be mixed or re-recorded independently.

Noise Shaping: An audio tool for creating digital dither allowing added noise to be shifted into those parts of the audio spectrum where the human ear is least sensitive. See Dithering.

Nonlinear Recording: Describes digital recording systems that allow any parts of the recording to be played back in any order with no gaps. Conventional tape is referred to as linear, because the material can only play back in the order in which it was recorded.

Normalization: An automatic process available in most audio software whereby the gain of all program material is adjusted so the peak level will just arrive at 0db. This can sometimes cause noise to enter into the recording if the recording levels are too low. There are many software programs such as BIAS’s Deck for OS X that allow normalization to very quickly correct an audio file that has been recorded at improper levels.

Notation Software: A computer program, capable of displaying and printing MIDI information as standard musical notation. Although sequencers can include notation capability, they lack the sophistication of true notation programs which often have scanning capabilities allowing quick input of music for transposing to another key.

Nyquist Frequency: The highest frequency that can be reproduced accurately when a signal is digitally encoded at a given sample rate. The theory being, Nyquist frequency is half of the sampling rate. As in, when a digital recording uses a sampling rate of 44.1kHz, the Nyquist frequency is 22.050kHz. If a signal being sampled contains frequency components that are above the Nyquist limit, aliasing will be introduced in the digital representation of the signal unless those frequencies are filtered out prior to digital encoding. See Aliasing.

Omni-Directional: For microphones is means receiving sound evenly from all directions. For speakers this means an even coverage in all directions.

Oscillator: An electronic device capable of generating recurring waveforms at different frequencies for testing purposes, or a digital process used by a synthesizer to generate a waveform.

Overdubbing: Enables one or more of previously recorded tracks to be monitored while simultaneously recording one or more signals onto other tracks. This process can be repeated until the song or soundtrack has been built up. If a mistake is made, it is possible to recue the tape to the desired starting point and repeat the process until you have the best take on tape. See Dubbing.

Oversampling: A digital filtering technique used in CD components where extra data points are added to the audio read from a disc, creating a signal that is some multiple (usually two, four, or eight times) of the CD format's standard sampling frequency. This process raises the frequency of any false information, which can then be removed by an analog filter. Using the high sample rate, the digital data may be processed with a very steep slope digital filter. As the filter is in the digital domain, unpleasant side-effects such as phase effects are eliminated.

Overtone: A whole-number multiple of the fundamental frequency of a tone. The overtones define the harmonic spectrum of a sound. See Partial.

PAM: Pulse Amplitude Modulation. In the first part of the A/D conversion, pulses occurring at the sampling frequency are modulated by an analog audio signal. See PCM.

Pan: To move a signal from the left to the right of a stereo field, or vice versa.

Pan pot: Round control knob enabling the user of a mixer to move the signal to any point in the stereo sound stage by varying the relative levels fed to the left and right stereo outputs. On most analog mixers there is a dent at the center between left and right on the pan knob. See Detent.

Parameter: A MIDI value seen in the envelope of a particular instrument that alters the integrity of the sound itself. Common parameters include pitch bend, sustain, volume, and reverb.

Parametric Equalizer: A specialized type of EQ that makes it possible to change the frequency range, bandwidth and boost or cut.

Partial: A single frequency, sinewave component (the fundamental, an overtone, or a tone at some other frequency) of a complex tone. All sounds are composed of a number of partials. See Harmonic.

Patch: A sequencer’s patch setting selects an instrument, thereby determining the nature of the sounds. Patch is exactly the same thing as an instrument or voice. Although most patches call up one sound or voice, a drum patch may encompass a large range of percussive instruments. Also when you plug in (or patch) cords between hardware components.

Patch Editor Software: A program which allows the editing of sounds by manipulating the envelope. Edirol’s PCR’s controller keyboards have their own editing software, to be used with any sequencer. Other programs, such as Sound Quest’s MIDI Quest allows you to edit, store and organize your patches.

PCI (Peripheral Component Interconnect): A computer expansion card interface used in PCs and Macs for adding video, networking or audio capabilities. Card D Deluxe, Digital Audio Lab’s soundcard, would be one such card.

PCMCIA: This is a memory or I/O (input/output) card for PC and Mac laptop computers. The acronym stands for the Personal Computer Memory Card International Association, a non-profit organization whose mission is to develop PC Card standards and promote adoption of PCMCIA-based products, however a more familiar explanation is “people can’t memorize computer industry acronyms.” Also known as PC cards, they can be found as memory cards on DAW’s, or communications ports on laptops for LAN, fax/modem, ATA disk drives, wireless internet connections and more. There are PCMCIA soundcards available such as Echo Audio’s newest Indigo.

PCM (Pulse Code Modulation): Digital audio recording format used since the late 1970s. PCM simultaneously captures all uncompressed bits of a Word (8 to 48-bits) at various standardized sampling frequencies (11kHz to 192kHz). The standard CD, co-developed by Philips and Sony, uses a 16-bit word length and a sampling rate of 44.1kHz. WAV and AIFF are common types of PCM audio files. See Word.

Peak: The highest point in the audio waveform on a graph of a sound wave that would look something like a mountain peak. It is the point of greatest voltage or sound pressure in a cycle.

Phase: Phase describes the time relationship between two different waveforms. It is expressed in degrees, with 360 degrees representing a full cycle. It is the amount by which one sine wave leads or lags a second wave of the same frequency. The difference is described by the term phase angle. Sine waves in phase reinforce each other; those out of phase cancel.

Pitch: A continuous frequency over time.

Pitch Bend Wheel: A MIDI controller that can vary the pitch of a sound and allows notes to be bent up or down like when sequencing a sliding trombone sound for instance.

Pitch to MIDI Conversion: Many programs have this feature whereby an audio signal is converted to MIDI data. This is especially useful in notation programs where the data can then be customized and printed. The audio signal needs to be monophonic, thereby having only one voice at a time. The best way to sell this feature regardless of the software being used is to state that the user will be able to hone his music theory with the editing of the file, as the conversion is normally far from perfect. Programs such as MakeMusic’s Finale Guitar have this feature specifically for the guitarist.

Plugins: These are accessory programs that add functionality to digital audio software. Ranging from input plugins that allow your player to read different file formats to output plugins that provide visual displays to accompany your music, to software samplers such as Gary Garitan’s Orchestral Strings.

Polyphonic: The ability to play many different notes at once.

Portamento: A musical term referring to the gliding effect that allows a sound to change pitch at a gradual rate, rather than abruptly. This is an effect that can be assigned using an assignable MIDI controller knob on controller keyboards such as the Edirol PCR-30 or PCR-50.

Polyphony: Derivative from the Greek term meaning variety of tones, it is the number of notes which can be played simultaneously. Any synthesizer has a maximum polyphony which cannot be exceeded. If the polyphony is exceeded, MIDI data will drop out from MIDI channels used near the end of the sequence.

Port: A hardware location where data is passed in and out. A port on a MIDI interface allows 16 MIDI channels to transmit data. The Edirol USB MIDI interfaces allow a variety of ports for the musician, with the UM-1 (or UM-1S) with 1 port, the UM-550 with 5 ports or the UM-880 with 8 ports. Although impractical within one sequence to utilize 128 channels (using the UM-880) it is beneficial to have a multiple port MIDI interface in the event there are multiple modules or keyboards in the MIDI setup.

Preamplifier: This is usually referred to as preamp and is a device that takes a source signal, such as from a turntable, tape deck or CD player, and passes this signal at line level on to a power-amplifier. The preamplifier may have a number of controls such as source selector switches, balance, volume and possibly tone controls. This is typically the largest gain stage in a sound set-up.

Pulse Wave: Similar to a square wave but non-symmetrical, pulse waves sound brighter and thinner than square waves, making them useful in the synthesis of reed instruments. The timbre changes according to the mark/space ratio of the waveform.

Punch Recording: A feature within audio software that allows automatic on-off recording at specified points…especially nice when you need to rerecord a short phrase in a vocal track to fix an entire vocal session.

Quantization: A sequencing editing operation that can be used to correct timing mistakes, quantization forces all notes played to fall on the nearest beat specified.

Real-Time: In sequencing software there are generally two types of recording procedures, real-time; and step-time. Real-time is literally recorded in time that has not been adjusted, such as slowed down. Step-time is a recording method of inputting MIDI data that is sequentially laid down note-by-note, chord-by-chord and is particularly helpful for inputting data at one’s own pace.

Red book: The formal standard for the audio compact disc (CD), developed by Philips and Sony in 1982.

Resolution: This is the accuracy with which an analog signal is represented by a digitized system. Although other factors affect accuracy of recording, the higher bit number used, the more accurately the amplitude of each sample can be measured.

Resonant Frequency: Any system has a resonance at some particular frequency and at that frequency, even a slight amount of energy can cause the system to vibrate. A stretched piano string, when plucked, will vibrate for a while at a certain fundamental frequency. Plucked again, it will again vibrate at that same frequency. This is its natural or resonant frequency. While this is the basis of musical instruments, it is usually undesirable in music-reproducing instruments like audio equipment or room acoustics.

Reverb: Acoustic ambience created by multiple reflections in a confined space. Also, a type of digital signal processing that produces a continuous wash of echoing sound, simulating an acoustic space such as a concert hall. Reverberation contains the some frequency components as the sound being processed, but no discrete echoes. See Echo, DSP or Delay.

Ripping: This is the process of taking audio data from a CD and making it into a sound file on your computer. It is called ripping because in most cases the audio data is digitally "ripped" directly from the CD. This process can be very fast (a four minute song might only take 30 seconds to record). An analog recording process on the other hand records a song by playing the CD and recording the sound output. The analog process can only happen in realtime (a four minute song takes four minutes to record). The digital extraction process is faster because it copies the data instead of recording the sound output. Software applications that rip from CDs create the new audio file in the WAV, AIFF or MP3 formats. Cakewalk’s Pyro is suitable.

Sample: A digital recording of a naturally occurring sound.

Sampling: Sampling is actually emulating the sound of an acoustical instrument by digitizing (converting to digital sound) the waveforms produced by the instrument. There are hardware samplers and software samplers, such as Tascam’s Gigastudio.

Sampling Rate: This is the rate at which samples of a waveform are made and must be twice the highest frequency one wishes to capture. Commercial compact discs use a rate of 44,100 samples per second. (Se Nyquist Theory)

Sequencer: A MIDI sequencer, whether it is a software program or a stand-alone sequencer, arranges melodic and harmonic patterns in successive positions, sequentially. Storing MIDI information such as note-on and note-off events in memory and playing them back in the most fundamental task of a sequencer.

Slider: An input-device to manipulate audio or MIDI data; a typical use is to increase or decrease volume. Programs will have this as an on-screen image, like a button control that one can move with a mouse.

Sibilance: High frequency whistling or lisping sound that affects vocal recordings, due either to poor microphone technique or excessive equalization.

SIMD: Programming code, Single Instruction Multiple Data.

Sine wave: This is the most basic waveform which is a pure tone with no harmonics and consists of a single partial. The sine wave forms the basis of all complex, periodic sounds.

SMPTE: (Society of Motion Pictures and Television Engineers) a.k.a. "Time Code.” Universally used and recognized standard for time and velocity. Digital machine code which contains hours, minutes, seconds and frames. Common formats in the US are 30 frames/second non-drop, and 29.97 frames/second drop-frame.

Software Synthesizers: These have become incredibly popular due to the fact that computers with lots of processing power have become affordable to everyone. Products such as Arturia’s Moog can provide the user with a specific sound set, suitable for a particular composition. Bitheadz has a wide variety of synths such as Harry Sharpe Guitars that can be interfaced as a plug in. See Synthesizer.

Sound Module: Another term for MIDI sound generator, this refers to the synthesis component in a device such as a keyboard that produces the sound such as a violin or piano.

Spectral Balance: This is the balance across the entire frequency spectrum of the audio range.

Square Wave: A symmetrical rectangular waveform which contain a series of odd harmonics.

Standard MIDI File: Usually seen as SMF files, this means that the MIDI file utilizes common parameters across different platforms and sequencers, such as the drums always being on MIDI channel 10. The significant advantage to this file format is assured compatibility regardless of what synth is used for playback.

Status Byte: In a MIDI message, this announces what kind of message is being sent, such as "note-on” or “note-off.”

Streaming Audio: Refers to the process of making a broadcast of audio available on the Internet.

Subcode: Hidden data within the CD and DAT format that includes such information as the absolute time location, number of tracks, total running time and so on.

Subtractive Synthesis: The process of creating a new sound by filtering and shaping a raw, harmonically complex waveform.

Synthesizer: A synthesizer is a device driven by a microprocessor which contains a programmable chip. Originally, a synthesizer produced an audio signal by the direct manipulation of electrical signals. Now MIDI sound-generating circuitry utilizes mathematical functions which alter a stream of digital numbers.

System Messages: MIDI data which is not specific to any one channel. System data includes system exclusive messages (an instrument’s internal data, sometimes called bulk dump data), system realtime messages (sequencer start, stop, and continue commands as well as MIDI clock and other timing information) and system common messages (song select, tuning requests, system reset, etc.).

SYSEX: System Exclusive Messages or Sysex messages do exactly what is implied - they send commands specific to a particular device in a MIDI setup where global control of all settings is not desired. They are particularly useful if your MIDI modules or keyboards are in a chain and isolated commands are necessary.

Tempo: The rate of speed at which a musical composition proceeds (i.e. the beat). Usually uses a quarter note as the timing reference.

Timbre: The quality of a sound that distinguishes it from other sounds of the same pitch and volume. It is the distinctive tone color of an instrument or a singing voice.

Tone Generator: This is essentially a synthesizer without a keyboard. A keyboard-less device which outputs audio signals in response to MIDI commands. Both the Edirol SD-20 and the SD-80 are tone generators.

Track: In audio software, tracks generally contain one audio layer or audio file; there is multi-track software or stereo (2 track) audio software. With MIDI sequencing, tracks are nothing more than an organizing tool commonly confused with MIDI Channels which are necessary for delineating different instruments. Although only one MIDI channel can be used at a time, many tracks can be assigned to this same MIDI channel. This is particularly useful when parts come in or fade out as these tracks can then be easily muted or soloed. Most sequencers allow an unlimited number of tracks within each song.

Translator: Software such as Chicken System’s Translator that allows conversion between professional sampler formats such as Akai.

Transient: Usually the brief initial (or attack) portion of a waveform. Transients provide important cues that help our ears recognize sounds, but they are often difficult for an audio system to reproduce because of their high amplitudes and short rise times.

Transparency: This is a listening term used to describe audio quality where the high frequency detail is clear and individual sounds are easy to identify and separate. The more transparent a sound is… the clearer the auditory picture.

Transpose: This allows a musical composition to be played in a different key. Both synthesizers and sequencers can carry out this function.

Tuning: 440 Hertz is the normal Western tuning value however, this can be easily be adjusted in a synthesizer to suit the type of music being performed. The pitch can be altered by raising or lowering the value as plus or minus cents. Playing non-Western music may dictate the need to adjust the tuning of a synth.

Tweeter: This is the smaller speaker within a speaker cabinet used to reproduce the higher range of frequencies. To form a full-range system, a tweeter needs to be combined with a woofer, (2-way system), or a woofer and midrange, (3-way system). The Edirol MA-20 desktop speakers have a 1” tweeter and a 4-3/4” woofer.

USB: 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.

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.

Vocoder: 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.

VCA: Voltage Controlled Amplifier. 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.

VU meter: 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.

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

Waveform: A representation of a wave's amplitude over time.

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.

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.

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

Word: One sample of audio data.

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 clock: The metronome that governs sample timing is called the word clock and is important because precise timing of digital audio samples is critical when linking digital audio equipment.

XLR: A 3-pin male/female connector originally developed by Canon that is commonly used to carry balanced analog audio signals for microphones. 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.

glossary courtesy of Edirol Corporation North America