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Music Technology & Home Recording Glossary E

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EARLY REFLECTIONS: The first sound reflections from walls, floors and ceilings following a sound created in an acoustically reflective environment.

Earth Loop: - see Ground Loop.

Earth: - see ground.

Echo - a very basic effect produced by repeating a sound with a delay long enough to be heard as a separate event. It is often just called delay and is usually used to add more depth to an audio signal without the muddiness often introduced by reverb. The repetition of a sound delayed in time by at least 50 milliseconds after the original. An effect often found in synthesizers and samplers.

Edit: To change or modify information. To change parameters or alter existing data.

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. 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.

EFFECTS LOOP: Connection system that allows an external signal processor to be connected into the audio chain.

Effects or "F.X." Processing: - Processing of audio signal in order to:

Effects return: - Connector, control, and/or path where a processed (wet) signal from an from a signal processing device enters a mixer. The enables the level of influence of the "wet" signal to be influenced via a potentiometer on the mixing desk. Additional mixer input designed to accommodate the output from an effects unit.

Efficiency: - With loudspeakers, efficiency is generally the Sound Pressure Level (measured in Decibels) produced from a given watt of an amplifiers signal (dB's per Watt). A very efficient speaker can have a bigger influence on the SPL's produced by a system than the level of watts produced by the amplifier. A good rule of thumb is that a speaker that 3 dB's more efficiency per Watt that another speaker will be twice as efficient, and will be capable of producing the same amount of dB's from an amplifier with say, a 50 Watts power output, as the less efficient speaker would with an amp which has a hundred Watts power output. To put it another way if one speaker has an efficiency rating of 100 dB's per Watt, and another speaker has an efficiency of 103 dB's per Watt, the second speaker will not be @ 3% more efficient, it will be @ 100% more efficient!

Electret Condenser microphone: - Condenser microphone where the condenser / capsule is kept in a constant state of charge. A condenser microphone that uses an electret (electrical-magnet) to hold a permanent electrical charge, enabling it to function in low-voltage.

EMF (ElectroMotive Force): - See Voltage.

ENCODE/DECODE: A system that requires a signal to be processed prior to recording, then that process reversed during playback. The process of converting any audio format to MP3

Enhanced CD: An important new product category, enhanced CDs are compatible with both audio CD players and properly configured computer multimedia ROMs, and can include video clips, still pictures, interviews, discographies, lyrics and other information, in addition to the recorded music.

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

ENVELOPE - changes in a sound over time, including alterations in a sound's amplitude, frequency and timbre. Used in sound synthesis to control the volume, pan, pitch or other attribute of sound over a period of time. ADSR envelopes are the most commonly used type of envelope. They are divided into several segments, Attack, Decay, Sustain and Release. The attack segment is often triggered by pressing a keyboard note. The envelope continues and holds the sustain level until the keyboard note is released, which causes the release segment to finish the envelope. The characteristic change in amplitude throughout time which all sounds possess. The envelope of a sound has a number of features: whether it sustains like a bowed violin string; whether it decays like a plucked violin string or a single strike of a drum; and how quickly the sound reaches its fullest intensity - how the sound "attacks". While the envelope of any specific sound has specific characteristics determined by the way the sound was generated, it should be realised that real sounds occur in real situations and the envelope of a sound will change according to the environment it occupies. A clave in a cave may appear (what is the sonic equivalent of the eye-based "appear"?) to have a longer envelope than when it is played in the open air. 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. A device which produces a control signal which varies in level with time. The simplest of these (sometimes called ADSR) has four parameters: Attack Time, Decay Time, Sustain Level & Release Time. Thus it has three time constants and one level constant. Such a device is often found on synthesisers, where it is usually used to control the volume of an amplifier, the cut off frequency of a filter, or the frequency of an oscillator. More complex arrangements involving a series of time and level constants are available, particularly on digital synthesisers. These are called multistage envelopes and may involve eight or more parameters usually in time and level pairs. A circuit capable of generating a control signal which represents the envelope of the sound you want to recreate. This may then be used to control the level of an oscillator or other sound source, though envelopes may also be used to control filter or modulation settings. The most common example is the ADSR generator. A circuit, usually triggered by pressing a key on a keyboard, that generates a changing voltage with respect to time. This voltage typically controls a VCF or VCA. An AHDSR and ADSR are two types of Envelope Generators. See ADSR.

E-PROM: (Erasable Programmable Read Only Memory) Similar to ROM, but the information on the chip can be erased and replaced using special equipment.

EQ: (Equalization) Sophisticated tone controls which can subtly enhance or drastically change a sound. Can make a sound "brighter", "darker", "fuller" or give you the "telephone effect" (tinny). Controls include selecting frequency to be affected, bandwidth and amount of boost and cut.

Equal Temperament A system for dividing an octave into 12 pitch steps, each of 100 cents. This has the effect of making all semitones equal in size. This became necessary once keyboard and fretted instruments became popular. It should be understood that the note A which appears in F# minor should have a slightly different frequency from the note A which appears in C major (this fine distinction is one of the reasons that pitch and frequency are not quite synonymous). This would normally be dealt with automatically by a proficient player on an instrument with continuous pitching such as a violin. A keyboard instrument would properly have to be tuned to a particular key, if music was then played in a different key, some or many of the intervals sounded would be flat or sharp. However since it was not convenient to retune these types of instruments correctly whenever a new key was required, various compromises were attempted. Equal temperament was one such compromise whereby the error was distributed equally between all the notes. This made the performance of music in different keys possible on the same instrument without retuning, in celebration of which J. S. Bach wrote not one, but two books, each of 24 preludes and fugues (a prelude and fugue in both the major and minor forms of 12 keys). A Scaling system where the octave is divided into 12 equal parts. The ratio of the frequencies between any two adjacent notes is exactly the same. Most keyboard instruments are scaled in this manner.

Equalisation or "EQ": - Signal processing device which alters the frequency response of an audio signal. There are several types of equalisation, notable examples being "Graphic EQ" and "Parametric EQ". Equalisation may be used to help acheive the desired "flat" response in a performance / recording (perhaps to correct acoustic defincies in the local environment), or used to alter more un natural levels of frequency response as an effect in itself (modern djs / remixers tend to like doing this alot). Device for selectively cutting or boosting selected parts of the audio spectrum. (EQ) - boosting or cutting various frequencies in the spectrum of a sound. (EQ) - a device used to cut and boost individual frequencies of an audio signal using a number of filters. The name "equalizer" comes from the original application of correcting distorted audio signals to sound closer to the original source. Graphic and Parametric are different types of equalizers used by audio equipment and software plug-ins.

ERASE: To remove recorded material from an analogue tape, or to remove digital data from any form of storage media.

ERROR CORRECTION - a procedure found in digital audio systems that detects and correct inaccurate or missing bits in the data stream.

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

Event: - Any single piece of MIDI data is referred to as an "event", eg a note being triggered, the velocity of the note, a program change etc. 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.

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.

EXPANDER MODULE: Synthesizer with no keyboard, often rack mountable or in some other compact format.

Expansion and Expander:- A form of Dynamics processing. When lower level signals are lowered (attenuated) and higher level signals are raised (boosted), this is expansion. A devise that acheives this through circuitry or software is called an expander. This is the opposite of compression. A devise designed to decrease the level of low level signals and increase the level of high level signals, thus increasing the dynamic range of the signal.

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