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Layering: The ability to place or stack two or more sounds on the same area of the keyboard to create a denser sound.

LCD - Liquid Crystal Display. A small screen found on electronic instruments that displays data.

LED: Light Emitting Diode. A form of solid state lamp.

LFO - a low frequency oscillator that is used to alter a sound's frequency or amplitude. Low Frequency Oscillator. An oscillator used for modulation whose range is below the audible range (20 Hz). Example: Varying pitch cyclically produces vibrato.

LIBRARIAN - a category of MIDI software that is used to organize and store a MIDI device's patch (program) data.

Limiter: - Signal processing which sharply cuts off output once it reaches a certain preset level. Roughly it is a form of compression (see dynamics processing) with a very high ratio (10/1 or over) used mostly for for the protection of ears loudspeakers etc.

Line level signal: - For an audio device which uses unbalanced inputs / outputs, a line level signal is a signal with a level of -10dBV (0.316 volt). for a device which uses balanced inputs / outputs, it is a signal whose level is at +4dBm (1.23 volts). A nominal signal level which is around -10dBV for semi-pro equipment and +4dBu for professional equipment.

LINEAR: A device where the output is a direct multiple of the input.

Load (Computing): - Copy data from persistent storage (Hard Disk, Floppy etc) into RAM memory.

Load / Load Impedance: - Electronically, a load is burden placed in terms of resistance to the signal from an electronic circuit (eg loudspeaker / crossover from another circuit which is supplying the power (eg amp). The impedance is the measurement of this resistance in terms of Ohms.

LOAD: Electrical circuit that draws power from another circuit or power supply. Also describes reading data into a computer.

Loading: To transfer from one data storage medium to another. This is generally from disk to RAM memory or vice-versa, as opposed to saving from RAM to disk.

LOCAL ON/OFF - a three byte channel message that determines the status of the Local On function of a MIDI device. LOCAL ON allows the instrument to produce sounds from incoming MIDI data and its own keyboard. LOCAL OFF states that only external MIDI data is responded to.

Lock: To prevent data from being edited, discarded or renamed, or to prevent entire banks or disks from being altered.

LOGIC: Type of electronic circuitry used for processing binary signals comprising two discrete voltage levels.

Longitudinal time code :(LTC): Time code which is recorded onto an audio or video cue track. LTC encodes the biphase time-code signal onto an analog audio or cue track as a modulated square-wave signal

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. At its most basic, a loop is a series of instructions (computing) or beats / notes / chords (music) that is capable of constant repetition, consistently having the same result. Musically this will usually be a short piece measured in terms of a bar or more, which will seamlessly repeat without any musical / tempo inconsistencies, annoying clicks etc. Looping: Looping is the process of repeating a portion of a sample over and over in order to create a sustaining sound. The looped sound will continue as long as the key is depressed. A sound is usually looped during a point in its evolution where the harmonics and amplitude are relatively static in order to avoid pops and glitches in the sound.

Low Frequency Oscillator - used in sound synthesis to modulate a sound attribute such as volume at an audibly slow rate. (LFO): An oscillator used as a modulation source, usually below 20Hz. The most common LFO waveshape is the sine wave, though there is often a choice of sine, square, triangular and sawtooth waveforms.

Low Note Priority: When more than one note is played on a monophonic synthesizer, only the lowest note will sound.

LOW PASS FILTER (LPF): A filter which attenuates frequencies above its cutoff frequency. A filter which attenuates frequencies which are above it's stated cutoff frequency. See also "Crossover". 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.

LSB: Least Significant Byte. If a piece of data has to be conveyed as two bytes, one byte represents high value numbers and the other low value numbers, much in the same way as tens and units function in the decimal system. The high value, or most significant part of the message is called the Most Significant Byte or MSB.

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