LA synthesis. See linear arithmetic synthesis.

lag processor. An analog synthesizer module somewhat similar to a compressor for control voltages—a lag processor smoothes out peaks in control voltage signals.

LAN. Local Area Network. A number of computers and peripherals in a building or limited area that are interconnected into a network.

land. 1. The area between the pits in a commercially duplicated (which are usually stamped) compact disc. 2. The area between the spirals of the groove in a vinyl LP record.

lane. An area in a DAW window associated with a particular track and dedicated to displaying volume, pan, velocity, or another parameter related to the MIDI notes or audio data in the track. See Figure L.1.

Figure L.1. A lane is used to display control information related to the MIDI or audio data in a track. In this case, MIDI notes are shown in the top section, while velocities are shown in the bottom lane.

large-diaphragm microphone. A microphone with a diaphragm measuring 3/4-inch or larger in diameter. Most large-diaphragm mics are condensers, though there are a few large-diaphragm dynamic microphones. The large-diaphragm design has more surface area than small-diaphragm designs and is therefore often more sensitive. Large-diaphragms are popular for many studio applications because they have a wide frequency range and an associated “big” sound that works well for vocal and many instrumental applications.

laser. Light Amplification by Stimulated Emission of Radiation. A device that produces “coherent” or extremely focused light. In audio, lasers are used for burning and reading optical discs, such as various types of CDs and DVDs.

latency. Any number of time delays, such as: 1. A time delay resulting from an audio signal passing into a DAW when recording audio, then passing back out in order to be monitored by the performer. This type of latency is a critical problem when tracking or when overdubbing on top of existing tracks. 2. The time required for a plug-in to process a signal in a DAW. This type of latency is a critical problem when using plug-ins for parallel processing, and correcting it is essential for maintaining stereo imaging and phase accuracy. 3. The time delay between a MIDI note on message and the note actually beginning to sound. 4. The time it takes for a hard drive to locate and retrieve a piece of data. This type of latency is critical to high-demand applications, such as multitrack audio recording and playback.

latency compensation. A function of most DAWs that corrects for the latency (timing delays) introduced when using plug-ins to process tracks in a multitrack production.

latency-free monitoring. A technique for eliminating the time delay between when a sound enters a DAW to be recorded and when it comes back out in order to be monitored by the musician or performer. Various methods are used, such as monitoring signals through an external mixer before they enter the DAW or using DSP processing power in the computer’s audio interface to compensate for signal latency. See Figure L.3.

Figure L.2. The late reflections portion of a reverb is the wash of ambience that occurs after the early reflections.

Figure L.3. A mixer can be used to monitor signals that are being recorded, eliminating the problem of latency when tracking or overdubbing.

late reflections. The complex, diffuse “reverberation” or wash of ambience portion of a reverb that occurs after the early reflections. The late reflections give our ears significant cues about the size of a room or space (see Figure L.2). See also early reflections.

launch. To start a computer program.

lavalier. A compact microphone designed to be worn attached to clothing. Lavaliers are typically used for speaking applications when a handheld or stand-mounted microphone isn’t practical—though creative recording engineers have used them for a variety of interesting applications.

layer. 1. In synthesizers or samplers, a single preset that is triggered by a specific range of values for a MIDI controller. By combining layers in different ways, the instrument can produce composite sounds or can switch or crossfade between layers set to the same MIDI channel using velocity or another MIDI controller. For example, a low velocity might trigger a soft piano sample. A medium velocity might trigger a medium-loud piano sample, and a high velocity might trigger a loud piano sample. Or, completely different sounds might be placed on each layer, or two layers might be set up to sound in response to the same velocity value. See also crossfade, cross switch. 2. In recording, to overdub parts to create a fuller sound.

layering. Combining two or more presets or sounds in a synthesizer or sampler to create a new composite sound.

LCD. Liquid Crystal Display. A material that changes the phase of light. Liquid crystals are placed between polarized plates that only pass light of a certain phase to create a “cell.” The liquid crystal material changes the phase of light passing through it under the control of electrical voltage so that it either passes through the polarized plate or is blocked. By combining a large number of cells into a matrix where each cell represents a pixel, a high-resolution, monochrome, or color display can be created.

LE. Limited Edition. 1. A feature-limited version of a piece of software often designed to hit a particular price point, intended for semi-professional users or intended as a demo for the full version. 2. A special version of a product that is manufactured in limited numbers, often with the idea of creating a “collectible” item.

leader tape. A short piece of non-magnetic tape (usually plastic or paper) that is spliced into a reel of analog recording tape to separate one song from another. Leader tape is also used at the beginning and end of a reel of tape to identify the end and beginning and to protect the reel.

lead-in. The area on a CD-R where the table of contents is written. See also TOC.

leakage. 1. Ambient sound created by a source that is picked up by a microphone placed on another source. For example, the sound of a drum set may leak into the microphones that are placed on a grand piano. 2. Sound escaping from headphones worn by a musician (usually a vocalist) that is picked up by the musician’s microphone. 3. The frequency of one tonewheel in an electronic organ being sensed by the pickup for an adjacent tonewheel.

least significant bit. See LSB.

LED. Light Emitting Diode. A semiconductor component that produces light when electric current passes through it. LEDs are widely used as indicator lights in all types of electronic gear. Newer, high-power versions are used for area lighting purposes.

LEDE. See live end/dead end.

legacy. 1. An older version of a software program. Most new versions are designed to be compatible with older, legacy versions of themselves. 2. Data that was created using an older version of a program. Most new versions of programs support opening and working with older legacy data.

legato mode. A synthesizer function where, if an existing note is held and a new note is played, the new note will not trigger another note attack. The existing note will remain in the sustain portion of its envelope and will be smoothly re-pitched to whatever the new note’s pitch might be.

Leslie. A family of rotary speakers invented by Donald Leslie and first produced in 1941. The original Leslie cabinet was designed to be used with Hammond organs. See also rotary speaker.

level. The volume or strength of a signal.

leveler. A dynamics processor that attempts to maintain a constant signal level, usually by applying compression. Most levelers have a long attack time that allows short peaks through; the goal is to maintain a usable dynamic range. The consumer versions of levelers are also known as automatic gain controls and are used for applications, such as keeping the level of television commercials the same as the program level.

Lexan overlay. A removable plastic sheet that fits over a control surface and that has labels to indicate the functions of the various controls when the control surface is used with a specific piece of software.

LF. See low frequency.

LFE. Low-Frequency Effects. The “.1” of a surround sound system, used to carry low-frequency information. The concept is to provide a separate driver and amplifier for the power-intensive low-frequency components of film and video sound effects, such as explosions.

LFO. Low-Frequency Oscillator. A type of oscillator dedicated to producing low-frequency audio signals that are used for controlling and modulating other oscillators or parameters on processors.

LFO waveform. The shape of the waveform produced by an LFO. The LFO waveform can greatly affect the sound of any modulation produced using the output from the LFO.

librarian. Software designed to store and organize presets for a synthesizer or other MIDI device. Librarians communicate with MIDI hardware using System Exclusive commands.

library. 1. A collection of presets for a synthesizer or other MIDI device. 2. A collection of sounds for a sampler, including program and sample data. Commercial sample libraries are available from a number of manufacturers and can be targeted toward a specific group of sounds (a library of solo strings, for example), or they can be more generic libraries that contain a variety of sound types. 3. A collection of audio or MIDI loops.

light-emitting diode. See LED.

Lightpipe (a.k.a. ADAT Lightpipe). A term used by Alesis for their eight-channel optical digital interconnection protocol, first introduced on the company’s ADAT eight-track modular digital audio recorders. Lightpipe uses the same connectors and cables as the two-channel TOSLink protocol, though the two formats are not compatible signal-wise. Though the ADAT has waned in popularity, Lightpipe has become an industry-standard format for multichannel optical connections.

limiter. A compressor with a very high ratio—10:1 or even higher—resulting in very little change in output level no matter how much the level of the input signal changes. A limiter is typically used to establish a ceiling level above which signals aren’t allowed to pass. Limiters are also used to raise signal levels without danger of pushing them into distortion. This is done by using the limiter to reduce the level of peaks, thus allowing the overall signal level to be safely increased. See also compressor.

line amp. A type of amplifier used to balance a signal and raise it to a level that can withstand long cable runs.

line conditioner. See power conditioner.

line input. An input on an audio device that is designed to accept line-level signals. In mixers and some types of preamps, the line-level inputs bypass the high-gain preamps necessary for microphone level signals, resulting in a shorter, purer signal path.

line level. Technically, any signal voltage greater than 25 millivolts RMS, though the range is in practice 100 millivolts up to 12 volts. The two common line levels in use today for professional and semi-professional audio are 0.316 volts (–10 dBV) and 1.23 volts (+4 dBu).

linear. A mathematical function or device response that is close to a straight line. Flat response, for example, is linear frequency response—the output level of each frequency equals its input level. The ear’s response to volume changes, however, is nonlinear—it is a logarithmic function. See also linearity.

Linear Arithmetic synthesis (a.k.a. LA synthesis). A type of digital synthesis developed by Roland for the D-50 and subsequent keyboards and modules. LA synthesis uses sampled attacks combined with synthesized waveforms for the other portions of each note. This allows efficient use of sample memory, as well as creative combinations of unrelated attacks and waveforms.

linear interpolation (a.k.a. averaging). A technique for correcting errors in a digital signal. The system averages the sample values before and after a corrupt or missing sample to provide an estimation of the value of the missing sample.

linearity. 1. The ability for an analog-to-digital or digital-to-analog converter to capture or reproduce signal levels accurately. 2. The ability of an amplifier to output signal levels in direct proportion to input signal levels. If a device is completely linear, the output-to-input signal ratio is constant, regardless of the input signal level.

linear phase response. A filter in which all the frequencies passing through are delayed by the same amount in terms of phase. A filter with linear phase response will not introduce audible artifacts into the sound that is passing through it. True linear phase response is not possible with analog circuitry; a digital filter is required. See also group delay.

linear taper pot. A potentiometer that changes resistance in a linear fashion. At 1/4 of its travel, the resistance is at 25%; at half of its travel, the resistance is at 50%; and so on, so in a technical sense, the resistance change is even. Linear taper pots are typically used to control parameters and settings other than volume, since our ears respond to volume changes in logarithmic fashion, and a linear taper pot sounds as if it is changing level at an uneven rate.

Linear Time Code. See LTC.

Linkwitz-Riley filter. A type of electronic crossover named for its inventors, Siegfried Linkwitz and Russ Riley. A Linkwitz-Riley crossover is created by cascading a low-pass filter and a high-pass filter. The big advantages to Linkwitz-Riley crossovers versus some other types are that the Linkwitz-Riley design results in an in-phase output signal and 0 dB of gain at the crossover point. (A Butter-worth crossover design, for example, has a 3-dB peak at the crossover point.) The “order” of the crossover indicates the steepness of the filter slopes. For example, a 2nd-order Linkwitz-Riley crossover cascades two 1-pole filters for a 12-dB/octave slope. A 4th-order Linkwitz-Riley crossover cascades two 2nd-order filters for a 24-dB/octave slope. An 8th-order Linkwitz-Riley crossover cascades two 4th-order filters for a 48-dB/octave slope.

Linux. An open source version of the UNIX operating system, originally created by Finnish programmer Linus Torvalds.

Lissajous phase meter. A type of meter used to display the relative phase and polarity of two or more audio signals. Named for Jules Antoine Lissajous, a French mathematician.

listenback. Speakers set up in the studio or live room so that the musicians can hear the playback of recorded tracks without coming into the control room.

listenback mic. A microphone set up in the studio or live room so that the musicians can communicate with the engineer and producer in the control room. See also talkback mic.

listening position. The position where the listener is ideally located when monitoring audio—in stereo this is typically the position that results in the listener forming an equilateral triangle with the two speakers.

live. In acoustics, a reflective space that has no absorption to control the acoustic response or reverb time.

live end/dead end (a.k.a. LEDE). Trademarked term for a type of studio design featuring absorption in the front of the control room and reflective surfaces in the rear of the control room.

live room. 1. A room constructed with all or mostly reflective surfaces, resulting in strong acoustic reflections and long reverb times. 2. A studio room where performers are recorded.

load. 1. In electronics, an impedance or circuit that is connected to the output from another circuit and to which power is delivered. 2. The manner in which a driver is connected to a speaker cabinet, especially a horn (often called a horn-loaded driver).

lobar polar pattern. A highly directional polar pattern found only in shotgun microphones. See Figure L.4.

Figure L.4. A shotgun microphone has a lobar polar pattern that can pick up distant sounds without interference from unwanted sounds.

lobe. A portion of a microphone polar pattern that is not omnidirectional (spherical) and that is divided into different parts by null or dead points where no sound is picked up. A common example is a figure-8 pattern, where there is a spherical lobe in front of the microphone and a spherical lobe behind the microphone, which are separated by a null to the side of the mic. The most extreme example of a lobe is a shotgun mic, which has an extremely long frontal lobe in its pattern for long-distance pickup. Wireless systems and loudspeakers can also exhibit lobing. See Figure L.5.

Figure L.5. A section of a non-omnidirectional polar pattern bounded by a null is called a lobe. In this hypercardioid polar pattern, there is a lobe to the rear of the mic (circled in the figure).

local area network. See LAN.

local control. A function found in most keyboards that connects or disconnects the keyboard’s keys from its internal sound generator. When local is on, the instrument’s keys will play the internal sounds. When local is off, the instrument’s keys will only be transmitted externally over MIDI, and the internal sounds will only respond to MIDI messages arriving at the MIDI in port. Local control is used to prevent MIDI loops, where the messages from a keyboard’s keys play the internal sound and are sent out over MIDI, and because of a loop, are also received at the MIDI input. The doubled notes will cut the polyphony of the device in half and will likely also sound “hollow” due to phase cancellation from the two messages arriving at slightly different times.

localization. The ability to pinpoint where a sound source is coming from.

local on/off. See local control.

locate. To navigate to a specific point in time on a tape or in an audio project.

locate point. A saved time location on a tape or in a project. The tape recorder, DAW, or other audio program can jump to the locate point with a single button press or mouse click. This provides easy navigation among the important sections in a song or project. See also marker.

lock. To slave to time code or clock signals. A device is “locked” when it is synced to time code or clock signal. Mechanical devices, such as tape recorders and video decks, typically require a short pre-roll period in order to get up to speed and to lock to time code. Non-tape-based digital devices usually lock almost instantly.

lock up. 1. To synchronize two devices. 2. A CPU-based device or piece of software that has suffered a catastrophic error and is frozen—it will not respond to commands or controls. The usual cure for a locked-up device is to reboot it or, in the case of a personal computer, force the problem application to quit or terminate.

look ahead. A feature found in some virtual dynamics processors (compressors and limiters) where the software can examine the approaching audio. This allows the processor enough time to prepare for and accurately respond to fast transients and large peaks.

loop. 1. A short segment of audio, such as a measure of a drum beat, that is set up to repeat. 2. A portion of a sample that is repeated in order to allow the sound to sustain longer than the original sample lasts. 3. A transport control that continuously repeats playback of a selected section of a track or project.

loop point. The beginning or end point of a loop.

loop recording. A function or operating mode in some DAWs and sequencers in which the program is set to repeatedly loop or play a section of a track—for example, from Bar 4 to Bar 8. Every time the program loops over the section, a new take is recorded to a separate audio file. This allows a musician or vocalist to make many passes without having to start and stop playback and recording for each pass.

loop slicing. A technique for slicing apart a piece of audio at transients. The slices can then be played back at faster and slower rates in order to change the tempo of the audio. Or, the slices can be rearranged or otherwise processed to create new sounds, rhythms, and effects. See also REX file.

lossless audio compression. A type of audio codec that reduces file size without compromising audio quality or removing data. Two common examples are FLAC (Free Lossless Audio Codec), an open source codec, and MLP (Meridian Lossless Packing), which is used with DVD-Audio.

loudness. Objectively, the measured SPL (sound pressure level) of a sound. Subjectively, loudness depends on the frequency and timbre of the sound and varies from listener to listener.

loudspeaker. See speaker.

low-cut filter (a.k.a. high-pass filter). A filter that reduces the level of frequencies below a certain point. Low-cut filters are used to reduce rumble, as well as boominess caused by excessive low-frequency levels.

low end. 1. A term used to refer to low frequencies and the bass range of the frequency spectrum. 2. A term sometimes used to refer to inexpensive equipment.

low frequency. A term used to refer to the lowest frequencies in the audio spectrum; there is no specific low-frequency range, though in general, the range of 20 to 100 or 150 Hz would qualify.

low-frequency oscillator. See LFO.

low impedance. An impedance of around 600 ohms or less. See also impedance.

low-level format. A type of formatting used to prepare a hard drive to store data. With a low-level format, the entire contents of the disk are erased, not just the directories (as with a high-level format). In most cases, the drive’s manufacturer will perform the low-level format; the user will only need to perform high-level formats.

low note priority. An operating mode on some synthesizers and samplers where the unit will only respond to and play the lowest note received over its MIDI channel. This is ideal if a player is using a piano patch on one keyboard and wants a module with a bass patch to follow along on the lowest pitches played, providing a simultaneous bass part.

low-pass filter (a.k.a. high-cut filter, treble control). A filter that reduces the frequencies above the cutoff frequency and allows frequencies below the cutoff frequency to pass through unchanged. See Figure L.6.

Figure L.6. A low-pass filter reduces the level of frequencies above a certain point, while allowing those below to pass through unchanged.

low-Z/Lo-Z. See low impedance.

LP. See low-pass filter.

LSB. Least Significant Bit (though technically “LSB” in all caps would refer to “Least Significant Byte”). The bit in a digital word that has the least impact on the mathematical value of the word and that determines whether the value is odd or even—typically the right-most bit.

LTB. Linear Time Base. A high-resolution system developed by Steinberg that provides for transmitting MIDI data with accuracy to 300 microseconds.

LTC. Linear Time Code or Longitudinal Time Code. Time code that is written as a continuous stream along a linear track on an analog audio multitrack or a video recorder. See also SMPTE Time Code, VITC.

lump in the line. A type of external AC power supply in which the transformer is in the middle of the cable that connects the device to the wall socket. Many studio owners prefer lump-in-the-line power supplies to wall-wart power supplies because they only require one space on a power strip—a wall wart can cover two or more spaces on a power strip.

lunchbox. A type of compact tabletop enclosure developed by API (Automated Processors, Inc.) and used to hold and power API’s 500-series audio processing modules (and compatible modules), such as compressors, equalizers, and mic preamps.

LVD. Low Voltage Differential. A technology that allows for higher speed, longer distance SCSI data transfer. Regular SCSI sends a series of voltage spikes and valleys that are interpreted as ones and zeros. With LVD, a signal and an inverse of that signal are sent over two wires, somewhat the same as balanced audio signals. The difference between the two signals is used to represent ones and zeros.