sabin. A measure of how well a surface or material absorbs sound per square foot. One sabin indicates complete absorption, with the usual reference being an open window. Sabin values for various materials range between 0 (perfectly reflective) and 1 (completely absorptive). Named for Wallace Sabin, an American physicist who studied acoustics in the late 1800s and early 1900s. He developed a measurement called the OWU (Open Window Unit) that became known as the sabin.

SACD. Super Audio Compact Disc. A consumer audio optical disc format developed by Sony that uses the Direct Stream Digital (DSD) technology developed by Sony and Philips. SACD uses a CD-sized disc and supports stereo and multichannel audio at sample rates up to 100 kHz, dynamic range of 120 dB, and 1-bit resolution. Though a large number of titles have been released on SACD (some having multiple layers also containing regular CD-compatible audio), the format has not seen large acceptance from the general public. See also Direct Stream Digital.

sample. 1. A single digital measurement of an audio signal. These measurements are stored as digital words with a certain bit depth or resolution. 2. The act of digitally recording an analog signal. 3. Digital audio in a sampler, sample-based synthesizer, or other device, such as a single sampled piano note, drum hit, or other sound used as part of a program or preset. 4. A generic reference to a sample-based preset in a sampler, drum machine, or other device, though that preset may in fact contain many individual samples (for example, “That’s a great piano sample!”).

sample-accurate. The ability of a device to synchronize or operate with sample-to-sample accuracy.

sample and hold. A circuit or module found in analog synthesizers that captures a voltage, then routes that voltage to control some parameter. (Filter cutoff frequency is a common control destination.) The “sampled” voltage remains constant until the next voltage is captured. This results in random voltages modulating a parameter in “step” fashion, jumping from one voltage immediately to the next.

sample CD. A collection of audio tracks, loops, or samples/sample-based programs on compact disc, intended to be used with a sampler, DAW, sampling drum machine, sample-based synthesizer, or other device.

sample clock. A clock that determines and drives the sample rate. See word clock.

sample dump. Transmission of the sample memory of one device into another device over MIDI connections. See Sample Dump Standard.

Sample Dump Standard (a.k.a. SDS). A standardized protocol for sending the contents of the sample memory of one device to another via MIDI. Sample dumps are commonly used to transfer the memory of a sampler into a computer for editing, or to transfer samples from a computer to a sampler. It can also be used to share samples among any number of samplers.

sample library. A collection of samples, whether for a hardware or software sampler, usually offered on CD-ROM or DVD-ROM by a soundware manufacturer. Sample libraries can range from a collection covering a particular category, such as an orchestral string library, to sound effects, to a general-purpose library that covers instruments, loops, and more.

sample offset uncertainty. See jitter.

sample-playback synthesis. A type of synthesis that is based on sampled waveforms or instruments rather than simple analog or digital waves. Because the sampled waveforms are generally stored in the synthesizer’s ROM, this type of synthesizer is also known as a “ROMpler.” See also ROMpler.

sampler. A hardware device that can capture digital audio recordings, distribute them across a key map or keyboard, and play them back at different pitches. Though a number of virtual instruments are referred to as samplers, most of these don’t actually “sample” in the traditional sense of taking samples of an analog signal.

sample rate. How many times per second samples are taken, transmitted, or played back by a sampler, processor, digital recorder, DAW, other digital audio device. Sample rate is generally given in kilohertz for PCM devices or in megahertz for DSD devices, though S/s (samples per second) is a more accurate measurement. Sample rate determines frequency response, as defined by the Nyquist Theorem, which says that the highest frequency that can be sampled is one half the sample rate. The standard sample rate for compact discs is 44.1 kHz. DAT and some other digital recorders operate at 48 kHz. High sample rates are two or four times the standard rates: 88.2, 96, 176.4, and 192 kHz.

sample rate conversion. The process of reducing or increasing the sample rate of a signal to another rate. Usually this is done in the digital domain, though it would, of course, be possible to convert the digital signal to analog, then resample at a different rate. The challenge is to make the conversion without changing pitch or sound quality. In some cases, the conversion was considered relatively easy—converting a 96-kHz signal to 48 kHz, for example. But the reality can be more complex, such as when converting from 96 kHz to 44.1 kHz or another non-integer multiple. Historically, sample rate–converted audio was considered to be of lower quality than the original source material, but some current algorithms are capable of extremely high-quality conversions.

sample rate converter. A hardware or software processor that converts digital audio recorded at one sample rate to a higher or lower sample rate. See also sample rate conversion.

sample word. A single sample or measurement of an audio signal represented as a group of bits. The number of bits equals the resolution of the sample. In a 16-bit system, a sample word would contain 16 bits, a 24-bit system uses words with a 24-bit length, and so on.

SATA. Serial ATA. A protocol for transmitting data to ATA drives serially at high speed, rather than in parallel fashion as in standard ATA. SATA allows for point-to-point connection of drives, eliminates master/slave drive settings, and simplifies termination issues. SATA supports cables up to one meter long, allowing for external drives. See also ATA.

satellite. A small speaker that is intended to be used with a subwoofer. The satellites produce the midrange and high frequencies, while the larger sub produces the low frequencies.

saturation. Originally, saturation was the maximum amount of magnetism that could be put on an analog tape; any more would result in distortion. Engineers carefully managed the levels going to tape for the compression, warmth, and fatness that came from approaching or reaching tape saturation. Saturation has come to be used as a term for overload distortion, whether in recording, guitar amps, or elsewhere.

sawtooth waveform. A cyclical waveform whose shape resembles a sawtooth. A sawtooth wave consists of a fundamental frequency and all (both odd and even) integer harmonics (see Figure S.1). The sawtooth wave is one of the basic waveforms available in analog synthesis (other common waves in analog synthesis include sine, triangle, and square). Sawtooth waves have a harsh sound, somewhat similar to a bowed stringed instrument.

Figure S.1. A sawtooth waveform contains a fundamental frequency plus all odd and even integer harmonics.

Scarlet Book. One of a set of “Rainbow Books” with colored covers containing the Sony/Philips-developed specifications for different optical compact disc formats. The Scarlet Book contains the specifications for SACD.

scene (a.k.a. snapshot). A memory location in a digital or digitally controlled mixer or other piece of gear that stores all the settings for the parameters in the device. A scene can be recalled, instantly resetting all the parameters to the values stored with the scene.

Schroeder diffusor (a.k.a. reflection phase grating). A Schroeder diffusor consists of a variety of wells of different depths but equal widths that scatter sound waves. The frequencies at which a Schroeder diffusor will operate depends on the depth of the wells; the wavelength of the lowest frequency the diffusor will affect is four times the depth of the deepest well. Named for Manfred Schroeder, a German professor of acoustics who discovered how to use number theory to determine the depth of the diffusor wells. The best known Schroeder diffusor is the QRD (Quadratic Residue Diffusor) type.

SCMS. Serial Copy Management System. A copy protection scheme developed by record labels for DAT recorders. Intended for the S/PDIF ports on consumer and semi-pro DAT machines, SCMS is a bit “flag” that does not allow digital copies to be made of digital copies. So, as many digital copies could be made of an original (first-generation) DAT tape as desired, but no digital copies could be made from any of those copies.

scooped mids (a.k.a. “smiley face” EQ). An equalization curve where the midrange frequencies are attenuated, resulting in emphasized low and high frequencies. Commonly found on consumer stereo systems. The standard EQ setting for certain types of heavy-metal guitar sounds. See Figure S.2.

Figure S.2. Cutting the midrange frequencies and either boosting or letting the high and low frequencies pass unchanged results in scooped mids.

score. 1. Notated music for a musician or ensemble. 2. The background and feature music in a film (a.k.a. film score) or play. 3. To create the music for a film or play. 4. To arrange or orchestrate a piece of music for an ensemble. 5. In certain software applications, the data required to play a piece of music. See also score window.

score window. An alternate way to view MIDI note data in a DAW or MIDI sequencer. A score window displays MIDI notes as standard notation (see Figure S.3). The notation can be edited by inserting, deleting, transposing, moving, or otherwise manipulating the notes. See also notation editing.

Figure S.3. The score window in a DAW or sequencer displays MIDI notes as standard musical notation. The notes can be easily edited using a mouse.

scratch (a.k.a. scratching). A technique used by DJs, where a vinyl record is manually moved forward and backward during playback to create a scratching sound.

scratch disk. A hard drive or partition used to temporarily hold data.

scratch mix. A rough or quick mix of a piece of music, often created as the tracks are being recorded. A scratch mix is not intended for public release, but is meant to be used by the engineer, producer, and musicians to evaluate performance, arrangement, or mix ideas, or is meant for demo purposes.

scratch track (a.k.a. guide track). A temporary track that is not intended to be used in the final mix. Typically, scratch tracks serve as reference material for overdubbing other parts and are replaced by real tracks later in the production process. An example would be a rough, scratch vocal track recorded so that the instrumentalists have a guide to refer to while recording their parts.

scratch vocal (a.k.a. guide vocal). A rough, temporary vocal track meant to serve as a reference when recording other parts to the song. The scratch vocal will be replaced with a final “keeper” vocal track later in the recording process. See also scratch track.

screensaver. A computer utility or part of the operating system intended to prevent an image from burning into a CRT screen when the computer is sitting idle for extended periods of time. Screensavers work by filling the screen with graphic images that randomly move about the screen. Though LCD screens do not suffer as much from burn in, screensavers are still in common use. See also burn in.

scribble strip. An area on a mixing console intended for labeling channel strips, aux sends and returns, buses, and other items. On digital and digitally controlled consoles, as well as control surfaces, the scribble strip has become a small LCD screen that displays the channel name and other information.

scroll. To scroll is to move through a window on a computer screen to display text that is too long or graphics that are too wide or long to fit completely within the window.

scroll wheel. A small wheel mounted in a computer mouse that can be rotated to scroll the data, text, or graphics within the active window on the screen. See also scroll.

scrub. To manually move backward or forward through a track to find a particular location. The term comes from the manner in which engineers would manually rock reels of analog tape back and forth while listening to the audio, which allowed them to precisely locate a point on the tape for editing.

SCSI. Small Computer System Interface. A hardware interface for connecting hard drives, CD-ROM/CD-R drives, removable drives, and other peripherals to devices such as computers, digital recorders, hardware samplers, and more. SCSI supports up to seven devices in a chain; the chain may be as long as 19 feet. SCSI-1, the original 8-bit-wide spec, has a throughput of 5 MB/second. Fast SCSI increases this to 10 MB/second, and Fast Wide SCSI doubles the bit width to 16 bits, for throughput of 20 MB/second. See also Ultra SCSI.

SD card. Secure Digital card. A flash-based memory card. SD cards feature encryption for secure data storage.

SDIF. 1. Sony Digital Interface Format. A digital connection format carrying audio over 75-ohm unbalanced coaxial cables terminated with BNC connectors. The original SDIF was made obsolete by SDIF-2, which used one cable for a single channel of data and another for word clock. For stereo signals, a second data cable is added. SDIF-3 is used for DSD transfers. 2. Sound Description Interchange Format. A standard for exchanging spectral description types developed by IRCAM (Institut de Recherchet Coordination Acoustique/Musique), CNMAT (Center for New Music and Audio Technologies), and IUA-UPF (L’institut Universitari de l’audiovisual-Universitat Pompeu Fabra).

SDII. See Sound Designer II.

SDMI. Secure Digital Music Initiative. A voluntary scheme developed by the RIAA for protecting digital music files.

SDRAM. Synchronous Dynamic Random Access Memory. A type of DRAM that can synchronize itself to the bus speed of its host computer. SDRAM is faster than standard DRAM. See also DRAM.

SDS. See Sample Dump Standard.

SE. Special Edition. A limited, modified, expanded, or extended version of a standard product. A special-edition audio product might contain improved parts, additional capabilities, bundled software or hardware, or other offerings beyond what you would get with the regular version.

sector. A section of a track on a hard drive or other media identified by a specific address. The drive uses the address to locate the sector, which is used to store and read data. Hard drives store from 512 bytes to 4 KB or more of data per sector. The address information is stored in a special sector (Sector 0), in a file known as the FAT (File Allocation Table).

seek time. The amount of time it takes for a device such as a hard disk or optical drive to locate a specific piece of data. With hard disks and optical drives, seek time is the time required for the drive to move its read/write heads from one track to another. Seek time, together with rotational delay and transfer time, comprise a device’s access time.

self-noise. The background noise generated by a device’s electronic components. Any device or system containing electronics will create some level of background noise. See also noise floor.

semi-open. A headphone design that allows some outside sound to pass into the wearer’s ears. Although semi-open headphones don’t isolate as well as fully closed headphones, many users consider them to be more comfortable to wear and use.

semi-parametric. See quasi-parametric.

semi-pro. Short for semi-professional. In audio, products intended for home and lower-level project studio use. The lines between consumer, semi-pro, and pro have blurred, but typically, semi-pro equipment is not as heavy-duty as professional equipment and may have more basic digital connectivity and unbalanced analog connections. Most semi-pro gear also operates at –10 dBv levels, rather than +4 dBu. See also consumer, professional.

semitone (a.k.a. half step). The smallest interval used in Western music. In the standard Western equal temperament, the octave is divided into 12 equal-sized semitones of 100 cents each. Other temperaments use semitones of varying sizes.

semi-weighted action. A keyboard instrument key action that has some resistance to being pressed—more than an unweighted synth or organ key, but not as much as a weighted or hammer-based piano-style action. See also action.

semiconductor. A solid material, such as silicon, germanium, and gallium arsenide, with limited ability to conduct current. Semiconductors are used to create electronic components, such as transistors and diodes. In some cases, such as transistors, the conductivity of the device can be controlled by an external voltage, such as an analog audio signal. See also diode, transistor.

send. See aux send.

sensitivity. 1. The amount of voltage a microphone produces for a given sound pressure level, usually specified in millivolts per Pascal (mV/Pa). 2. The input level necessary to drive a device to its rated output level. Higher sensitivity makes a device better able to deal with low-level signals, but may result in overload with louder signals.

sequence. 1. The act of recording MIDI data. 2. A recording of MIDI data that can be played back to control MIDI hardware or software synthesizers, samplers, or processors.

sequencer. A hardware device or computer software that can record, edit, process, manipulate, create, and play back MIDI information. Many of the popular commercial sequencers have evolved into DAWs with the addition of support for audio recording, editing, processing, and mixing features.

serial. 1. Data that is transmitted in sequential fashion, in a single stream arranged with one piece of information following another. 2. Events that occur one after another. See also series, parallel.

serial ATA. See SATA.

serial number. A unique number assigned to a piece of gear or software by the manufacturer for identification purposes.

series. 1. An arrangement of items one after another. In audio, each signal path is often arranged in series format, with the first piece of gear feeding the second, which feeds the third, which feeds the fourth, and so on. 2. A category or line of products that share similar features. 3. A musical tone row or arrangement of pitches. See also parallel.

server (a.k.a. file server). A computer or program that functions as a central repository for files and makes them available to other programs or computers on a network.

session. 1. Short for recording session. The time when musicians are working in a studio. 2. In certain audio applications, such as Digidesign Pro Tools, the master project document.

SFX. Short for special effects.

shared library. The Macintosh term for a DLL. A collection of software resources that is available to other programs.

shareware. Copyrighted software created by an individual or company and offered for free download. Typically, the user is granted a trial period. If the user continues to use the software after the end of the trial, the software creator requests a goodwill offering of cash to help defray development and other expenses. See also freeware.

shedding. 1. Short for woodshedding. Practicing a musical instrument. 2. A problem exhibited by some recording tape, in which oxide flakes off of the tape backing. A variety of factors affect how much a given piece of tape sheds, including age, quality of the tape, how often the tape is played, how the tape is stored, and more.

shelf. An equalizer or filter band that cuts or boosts all the frequencies above or below the cutoff frequency. See Figure S.4.

Figure S.4. A shelving EQ boosts or cuts all frequencies above a certain frequency.

shell. 1. A format converter that allows a host program to use unsupported plug-in formats. See also wrapper. 2. The layer of an operating system that accepts user input and provides user feedback.

shelving equalizer. An equalizer that uses shelving bands. See shelf.

shelving filter. A filter that uses shelving bands. See shelf.

shield. 1. Conductive material that is used to protect audio conductors and circuits from magnetic and electrostatic fields. For example, the signal conductors (internal wires) in audio cables are typically wrapped in metal foil or braided wire shielding to prevent them from picking up hum or other noise. 2. Magnetic material used to protect a CRT display from interference from other magnets, such as those in speakers. LCD and plasma displays are not affected by magnetic fields and require no shielding.

shielding. See shield.

shockmount (a.k.a. suspension mount, suspension basket). 1. Microphone mount designed to protect a mic from stand-borne vibration or impacts (see Figure S.5). A common type, sometimes referred to as a spider mount, uses a system of rubber or elastic bands to isolate the microphone from the stand. 2. Isolated rack rails or “case-within-a-case” rack designs that protect rack-mounted devices from vibration and impacts.

Figure S.5. A microphone shockmount isolates the mic from stand-borne vibrations or impacts.

shootout. Attempting to compare the quality and performance of a number of similar devices in order to find the best one for a particular application. Shootouts are very difficult to conduct, because it is essential to control the test conditions and parameters precisely for true results.

short. See short circuit.

short circuit. A failure in an electronic circuit, usually resulting from unintended contact between components or wiring.

shortcut. In the Windows operating system, an icon that points to another file. Double-clicking a shortcut finds the file the shortcut points at and launches it. Shortcuts are convenient for organizing files and folders. Known as an alias in the Macintosh OS.

shotgun microphone. A type of microphone featuring an extremely directional polar pattern. Most shotgun mics use long tubes to create acoustic phase cancellation that allows them to capture distant sounds without picking up surrounding sounds and noises. See also lobar polar pattern.

shuffle. A playback mode found on MP3 players, CD players, and other audio devices that plays the tracks back in random order.

shuffler. An electronic circuit used to decode MS signals to stereo, first described by Alan Blumlein and later expanded by Michael Gerzon. The shuffler combines the MS mid and side signals to create two results: the sum of the signals (A+B), which is created by mixing the signals, and the difference between the signals (A–B), which is created by phase reversing the B signal. There are a variety of ways that the sum and difference results can be panned and equalized to change the stereo width (sometimes referred to as spatial equalization) or to compensate for problems. See also MS stereo.

shuttle. A control on some tape decks, video decks, and control surfaces that serves as a manually controlled fast-forward and rewind function. Shuttle allows the engineer to quickly locate to a point in the track.

sibilance. The term sibilance comes from the Latin word for hissing. It refers to high-frequency vocal sounds, such as ss and sh, that live in the 5- to 10-kHz range. A de-esser is used to control excess sibilance in a vocal without removing high frequencies from the rest of the track.

side address. A microphone physically designed so that its diaphragm is parallel to the body of the mic, with the capsule oriented to pick up sound best from the side or sides of the mic, rather than from the end (see Figure S.6). See also end address.

Figure S.6. A side-address microphone picks up sound best from the side, rather than the end. In this case, you can see the round diaphragm behind the screen of the microphone.

sideband. A sum or difference frequency created when a sound wave (the carrier) is frequency modulated (FM) or amplitude modulated (AM). The upper sidebands result from the carrier and modulator adding, while the lower sidebands result from the difference between the carrier and modulator. For example, a carrier with a frequency of 1,000 Hz and a modulator with a frequency of 300 Hz would result in sidebands at 1,300 Hz (sum) and 700 Hz (difference). FM synthesis uses varying arrangements of carrier and modulator signals to create sidebands, which are shaped using different techniques to generate sounds.

sidechain (a.k.a. key, key input, or detector). An audio input used to trigger a compressor or noise gate’s operation. The audio signal coming in the device’s sidechain isn’t audible (at least not through the device, though it may be heard on another track or input); rather, the sidechain signal tells the compressor to process or the gate to open. A common use for a sidechain is to cause a compressor to reduce the level of background music in an ad when the voiceover comes in (referred to as ducking). Other uses include de-essing, dynamic equalization, special gating effects, and more. See also de-esser.

signal. 1. An electrical impulse, voltage, or current used to represent information. 2. In analog audio, a voltage representing an audio waveform.

signal path. 1. The route a signal takes through a series of pieces of equipment. 2. The devices an audio signal passes through while being recorded, mixed, or processed in a studio.

signal-to-noise ratio (a.k.a. SNR, S/N). 1. The ratio between the level of a desired signal and the self-noise of a piece of equipment. 2. In manufacturer spec terms, the difference between a device’s noise floor and its nominal, or normal, operating level. (Manufacturer signal-to-noise ratios are notoriously unreliable, due to different measurement methods and other factors.) The highest possible signal-to-noise ratio a device can have is equal to its dynamic range, though generally the ratio is based on a reference level lower than the maximum undistorted level possible.

silica gel. A desiccant, or moisture-absorbing compound, used to control humidity in packages containing sensitive electronic gear. (Those little white paper packets that are forever falling out of gear boxes...)

silk-dome tweeter. A high-frequency driver featuring a central dome made from silk cloth treated to be stiff enough to shape. Some listeners feel that silk-dome tweeters offer smoother sound, better damping, and less resonance, while others hear little or no difference when comparing them to metal-dome tweeters.

SIMM. Single In-line Memory Module. A type of SDRAM circuit board containing multiple memory chips allowing for easy installation. There were several different versions, such as 30-pin and 72-pin, composite and non-composite, different parities, all available in a range of total memory capacities. SIMMs were used in computers and hardware samplers, but have been replaced by DIMMs (Dual In-line Memory Modules) for most applications because SIMMs have a 32-bit data path used in older processors, whereas DIMMs have a 64-bit data path that is compatible with modern computers. See also SDRAM, DIMM.

simplex. A circuit or interface that allows one-way communication or transmission. Note that simplex is not the same as half-duplex, which allows for two-way communication, one direction at a time. A great example of simplex communication is a radio or television broadcast. See also half-duplex, full-duplex.

sine wave. A type of cyclical waveform containing a single frequency, the fundamental, with no harmonics or overtones. (See Figure S.7.) A flute is sometimes used as a sine wave, though in fact it contains a wide range of ultrasonic harmonics.

Figure S.7. A sine wave is the simplest waveform, containing just a fundamental frequency without any harmonics.

single-ended. A type of amplifier in which a single tube or transistor amplifies the entire signal. Single-ended amps are easier to design and use fewer components, but tend to have low power outputs. See also amplifier, Class A, Class A/B, Class B.

skin effect. The tendency of high-frequency signals to travel on the outer surface of a conductor.

skip-back sampling. A feature of some Roland samplers designed to prevent ideas from being lost. With skip-back sampling, audio is always being recorded, so you can go back and capture a certain amount of recently played material.

skirt. Frequencies beyond the selected band processed by an EQ, filter, or other device that are low in level, but still are processed. (See Figure S.8.) For example, in most EQs and filters, the processed band is determined by where the signal is 3 dB down from the rest of the signal. The skirt in this case would be the frequencies that extend past the 3 dB down point. The skirt is still affected by the processor but is not considered part of the bandwidth. See also 3 dB down point.

Figure S.8. The skirt contains frequencies that extend beyond the bandwidth selected. In this case, the dashed circle shows the skirt that extends beyond the cutoff frequency of a low-shelf filter.

slapback. 1. A short echo in a room resulting from a sound wave reflecting between parallel surfaces. You can test for slap echo by clapping your hands and listening for a discrete echo. 2. A popular echo effect on 1950s-era recordings, also popular on rockabilly and other styles of music. Slapback is a single delay repeat in the 40 to 150 ms range, set to be nearly the same volume as the original.

slap echo. See slapback.

slate. From the video term for the clapper used to identify a scene and sync point at the beginning of a shot. Audio slates are recorded at the beginning of tracks as either tones or vocal identification.

slatted absorber. See Helmholtz absorber.

slave. 1. A device that is under the control of another device. 2. To synchronize with, lock to, or chase a master sync device. 3. A device that is locked to and chasing a master device.

slave reel. When recording with analog tape, the only way to add tracks beyond the capacity of a single deck is to add a second slaved deck. To avoid the hassles of locking two decks together, a submix of the existing tracks is created on a new tape, known as a slave reel. Overdubs are then added to the slave reel and later mixed with the original reel. In DAW systems, slave reels have been replaced by virtual tracks.

sleep. A standby mode available on some devices, such as computers. Sleep mode turns off the video display, stops the hard drive, and turns off other active features. Power to the computer’s memory is retained so that applications can be left active and ready to go when the computer “wakes up.”

slew rate. The speed with which an amplifier or certain other types of gear can respond to changes in the input signal’s amplitude. Slew rate is important for accurately reproducing transients, dynamics, and high frequencies. Measured in volts/µs (microsecond).

slice. In the REX files created by Propellerhead ReCycle and other programs, the audio files aren’t actually stretched to change their tempo. Instead, the audio is chopped into small, rhythmic slices that can be played back at a faster or slower rate to change tempo, or certain slices can be deleted, copied, moved, re-ordered, or processed to change pitch or other parameters. See Figure S.9.

Figure S.9. In a REX file, the audio is chopped into rhythmic slices so that it can be played back faster or slower or otherwise manipulated.

slip cue. A DJ technique in which the stylus is placed on a vinyl LP, but the record is held stationary while the turntable continues to spin. The LP is released at the proper time and immediately begins to play.

slope. The rate at which frequencies past the cutoff frequency are attenuated by a filter. Slope is given in dB/octave. The order, or the number of poles in the filter, determines the slope, with each pole providing 6 dB/octave in attenuation. As an example, if the cutoff frequency is 5,000 Hz and the slope is 12 dB/octave (two poles), in the octave from 2,500 Hz to 5,000 Hz, the level would be reduced by 12 dB. The octave from 1,250 Hz to 2,500 Hz would be reduced by an additional 12 dB, from 625 Hz to 1,250 Hz another 12 dB, and so on. See Figure S.10.

Figure S.10. The slope of a filter is the rate at which the frequencies past the cutoff are reduced in level.

slot. See expansion slot.

small-diaphragm microphone. A microphone containing a diaphragm smaller than 5/8-inch or so. Small-diaphragm mics tend to respond well to high frequencies and transients due to the lower mass of the smaller diaphragm compared to a larger diaphragm. Small-diaphragm mics are commonly used for recording acoustic instruments, as drum overheads, for recording small and large ensembles, and other applications.

small-format mixer. A compact, portable mixer typically containing 16 or fewer input channels.

Smart FSK (a.k.a. SFSK, Smart Frequency Shift Key). An FSK signal that has added location information and functions more like true time code. Smart FSK allows the sequencer to locate to a particular time within a sequence. See FSK.

SmartMedia. A type of flash-based memory card developed by Toshiba, originally intended to replace the floppy disk and called SSFDC (Solid State Floppy Disk Card). The SmartMedia format was replaced by SD, xD (a.k.a. XD or Xd), and other card formats.

SMDI. SCSI Musical Data Interchange. A fast method developed by Peavey for transmitting the contents of the sample memory of a sampler to a computer using SCSI. SMDI has the advantage of being much faster than the MIDI Sample Dump Standard.

SMF. See Standard MIDI file.

smoothing. Interpolating between discrete digital values (which create a stair-stepped signal) to create a smooth, more analog-like signal. Smoothing can be applied to digital audio signals by a reconstruction filter in a digital-to-analog converter; it can be applied to MIDI controller messages, automation, or to any digital data.

smoothing filter. See anti-imaging filter.

SMPTE. Society of Motion Picture and Television Engineers. A professional organization for television and film audio engineers. Along with providing services to its members, SMPTE has helped develop measurement standards and the SMPTE linear time code system for synchronization. www.smpte.org.

SMPTE time code. An LTC (Linear Time Code) system developed by the SMPTE organization and used for synchronizing audio, video, synths, drum machines, and sequencers. (Trivia note: SMPTE time code was based on a system developed by NASA for tracking space travel.) SMPTE time code is based on video frames and a 24-hour cycle. For example, 01:02:52:27 means 1 hour, 2 minutes, 52 seconds, 27 frames. So, each frame and subframe has a specific address allowing different devices to be synchronized and specific points to be quickly located. Various frame rates are supported, including 24, 25, 29.97, and 30 frames per second.

S/MUX. Sample Multiplexing. A technology developed and licensed by Sonorus for transmitting high-resolution digital audio signals over low-resolution connections. S/MUX is similar to bit splitting, where a high-resolution audio signal is divided into two or more parts so it can be carried over a lower resolution connection. For example, a two-channel 24-bit/96-kHz digital audio signal might be divided so that it could carried or recorded on four 16-bit/44-kHz channels or tracks. At the destination or on playback, the stereo 24-bit/96-kHz signal would be reassembled. The primary difference between bit splitting and S/MUX is that S/MUX transmits each sample intact; it never divides samples. This allows certain types of processing to be applied to the split signals before they are reassembled. See also bit splitting.

snake. A multichannel audio cable. The traditional use for snakes has been to transmit a large number of signals from the stage to the mix position in live-sound venues. In this case, there is a stage box containing connection points for cables coming from mic- and line-level sources onstage. A long multi-core cable containing many separate internal cables runs from the stage box to the mix position, where the snake breaks out into separate connectors that plug into the mixer. Snakes are used in studios for connecting multitrack recorders to mixers or patch bays, audio interfaces to mic panels—anywhere a number of connections would ordinarily require separate cables to be run from place to place. It’s much more convenient and neat to run one snake cable than to run multiple separate cables.

snap. See snap to grid.

snap to grid. A type of quantization where events such as MIDI notes and audio regions are moved to the nearest location on a rhythmic grid.

snapshot. See scene.

snapshot automation. A type of automation found on some digital mixers, standalone digital audio workstations, and multitrack recorder/mixers, where automation commands recall snapshots. Snapshot automation does not provide continuous linear control over parameters, but it is a memory-efficient way to quickly change the parameter settings for a device. See also scene.

soffit. The underside of an architectural feature such as an arch, ceiling, or roof overhang. In studios, a soffit constructed on the front wall is often used to house the main monitor system.

soft clipping. Clipping is distortion that occurs when a signal’s level exceeds a device’s headroom. The signal can’t get any louder and is literally squared or clipped off. Soft clipping smoothes out the sharp “corners” of the clipped waveform, producing a gentler distortion that is less harsh and easier for high-frequency drivers to deal with.

soft knee. A feature of some compressors that gently begins to introduce compression as the signal approaches the threshold. This differs from standard, hard-knee compression, where the compression ratio is fully applied to the signal as soon as the threshold is crossed. Soft-knee compression is generally less audible, especially at high compression ratios. See Figure S.11.

Figure S.11. Soft-knee compression is less audible, especially with higher compression ratios.

soft limiting. A limiter that uses a soft-knee threshold approach to make the onset of limiting less audible. Soft limiters are often used to raise the average level of an audio signal without clipping or audible limiting. See also soft knee.

soft reset. A function of some devices that simulates powering the device off and back on without actually turning off the power. A good example is restarting a computer after a crash or other error. A soft reset may not clear all battery-backed settings and parameters; a hard reset (turning the power off and back on) is required to completely restore a device to its default state.

soft sampler. Short for software sampler. A virtual instrument that provides the capabilities of a hardware sampler. However, in many cases soft samplers don’t actually sample; they’re limited to loading and playing back samples and programs that use samples. Soft samplers offer several advantages over their hardware siblings, including more available RAM (depending on how much RAM the host computer contains); more polyphony (limited by the computer’s CPU); easy graphic editing of samples, keymaps, and programs; and streaming of huge samples that would be too large to fit into RAM from hard disk. See Figure S.12.

Figure S.12. Structure from Digidesign is a software sampler that offers powerful capabilities to Pro Tools users.

soft synth. Short for software synth, a.k.a. virtual instrument. A computer program that functions as a synthesizer or uses modeling to emulate a hardware synthesizer. As the power available in computers has increased, the quality and capabilities of soft synths have dramatically improved. Software synths may operate as standalone operations in the computer or function as plug-ins within a host program. Advantages of soft synths include high polyphony (limited only by available CPU power), storage and recall of all settings, automation of parameters, no physical space requirements or weight, and lower cost. See Figure S.13.

Figure S.13. Cakewalk’s Rapture is a software synthesizer that offers an array of sound design and performance options.

soft thru (a.k.a. software thru). A function in MIDI sequencers that routes MIDI data coming into a computer’s MIDI interface input back out to the interface’s MIDI out.

software. A set of specialized commands and operating instructions that tell a computer how to perform various operations and functions.

software patch. A piece of software intended to fix problems, add capabilities, or update a computer program.

solder. A metal alloy that melts at low temperatures and is used to mechanically and electrically connect components.

solid state. An electronic circuit constructed from solid semiconductor components rather than vacuum tubes.

solo. A function on a mixer that allows the engineer to monitor only the selected channel(s). Soloing mutes all the channels except the soloed channels without disturbing any other mixer settings.

solo safe. A function on a mixer that prevents a channel from being affected by the solo setting. A channel that is solo safe is not muted when another channel is soloed. This is useful for keeping effects returns and submix inputs from being muted when various channels are soloed.

Song Position Pointer (a.k.a. SPP). A MIDI System Common message that indicates how many sixteenth notes have elapsed since the beginning of a song. (This assumes the original resolution of 96 MIDI clock ticks or pulses per quarter note or six clock ticks per sixteenth note.) Song Position Pointer messages are not used to synchronize devices; rather, they allow a sequencer to locate to a specific point in a sequence. The Song Position Pointer message uses two data bytes that allow it to measure up to 16,384 values, which equals 4,096 quarter notes or 1,024 measures in 4/4 time.

Song Select. A MIDI System Common message that is used to tell a sequencer or drum machine to recall a particular song and prepare it to play.

sonogram. See spectrogram.

sonograph. Instrument that creates a spectrogram or sonogram.

sostenuto. 1. A foot pedal found on a grand piano. A sostenuto pedal causes notes already being held when the pedal is pressed to sustain after the notes are released, but does not cause notes played after the pedal is pressed to sustain. 2. MIDI Continuous Controller #66. The MIDI sostenuto controller turns on with a MIDI value of 127, off with a MIDI value of 0, and (unless remapped by the user) performs the same function as a piano’s sostenuto pedal.

sound. Vibrations/air pressure variations with frequencies in the range of human hearing.

sound barrier. 1. Material designed to stop the transmission of sound waves. 2. Also known as Mach 1. The point at which an object moves from transonic (speeds just above and below the speed of sound) to fully supersonic speed.

sound bite. A term used in some DAW programs to refer to a small piece or chunk of digital audio data.

soundcard. A board or card that mounts in an expansion slot inside a computer and provides analog and/or digital audio input and output capabilities. Soundcards may also have mic-level inputs, MIDI inputs and outputs, and other features. The term “soundcard” is more commonly used to refer to Windows-platform consumer audio cards, while semi-pro and professional units for Windows and Macintosh computers are generally labeled as “audio interfaces.”

sound check. A period of time before a performance when the setup and operation of a sound system is evaluated. This can range from testing microphones to setting levels to doing a trial performance by the full ensemble for the purposes of setting up EQ, effects, and monitor levels.

Sound Designer. A digital audio application created by Digidesign. Originally developed for sample editing, Sound Designer evolved into the software component of the Sound Tools stereo digital audio editing/recording system. See also Sound Designer II.

Sound Designer II (a.k.a. SDII). The digital audio file format used by later versions of Digidesign’s Sound Designer software. The SDII file format became popular on the Macintosh platform, though it has largely been supplanted by the Broadcast WAV file format. See also Sound Designer.

sound field. The range of panning or left/right stereo width available for positioning sounds. Surround sound formats expand this to include the range of front-to-back panning available.

sound isolation. A more technically correct way of saying “soundproofing.”

sound pressure level. The volume or loudness of a sound, expressed in decibels. The reference 0 dB represents the baseline threshold of human hearing. The range most recording engineers recommend working at in the studio is 80 to 90 dB, because our ears have the best response at this volume level.

Sound Transmission Class (a.k.a. STC). A rating that can be used to compare the acoustical isolation provided by different materials. In a series of tests, the sound transmission loss for a series of frequencies is plotted on a graph, the resulting curve is compared to a reference curve, and the STC rating is determined. For example, 1/2-inch gypsum board might have an STC rating of 28. It’s important to note that STCs of combined materials don’t add, so two layers of gypsum board on a wall do not result in an STC of 56. In this particular case, doubling the gypsum board doubles the mass, which results in an STC increase of 6, from an STC of 28 for a single board to an STC of 34 for a double layer of board. Normal conversation can be heard and understood through a material with an STC rating of 25 to 34. An STC of 65 or higher is considered soundproof by many listeners.

Sound Transmission Loss (a.k.a. STL). A frequency-dependent measurement of the amount of isolation from sound transmission a particular material provides. For example, 1/2-inch gypsum board might have a sound transmission loss rating of 15 decibels at 125 hertz, meaning that a 125-Hz sound wave passing through the gypsum board will be reduced in level by 15 decibels.

sound wave. 1. Wave motion created in air (or other material) as a result of vibration of a material in the human hearing range. 2. A cyclical pressure front consisting of a zone of high pressure (compression) followed by a zone of low pressure (rarefaction), followed by high pressure, and so on, propagating through air or other material.

SoundFont. A standard file format developed by E-MU Systems for storing sound information. SoundFonts contain samples, wavetable synthesis parameters and instructions, sample loop information, and real-time MIDI control response parameters and instructions. SoundFonts require a compatible player; the quality of the output will depend on the quality of the playback device.

soundproof. Impervious to sound waves. This is nearly impossible to achieve without extensive construction, extremely heavy mass, and great expense.

soundset. A group of presets or programs.

soundstage. 1. Also known as studio. A room used for audio production. 2. The sonic space that a recording lives in, or the perceived room or space that listeners hear in the tracks of a recording.

soundware. Sounds developed for synthesizers and samplers. Though any synth, sample patch, or sound is technically soundware, the term is generally applied to sounds developed and offered for commercial sale.

source. 1. In audio, the instrument or object producing a sound. 2. The signal path selected to be monitored by a recorder, audio interface, or VU or other meter, or that is selected to play through a monitor system.

source code. The instructions making up a computer program. Typically, source code must be compiled, or translated to the language the computer’s specific process can use.

spaced omni. A stereo microphone technique first used by Harry Fletcher in 1933. The spaced-omni technique uses two identical omnidirectional microphones placed several feet apart (see Figure S.14). With careful placement, spaced omni offers a good balance of room ambience and direct source sound, with tonally natural response. See also A-B stereo.

Figure S.14. For the spaced-omni stereo miking technique, two omnidirectional microphones are positioned in parallel in front of the sound source, spaced several feet apart.

spare bedroom. The most common location for a home studio.

SPARS. Society of Professional Audio Recording Services. An organization made up of audio and multimedia businesses, business owners, engineers, and other industry professionals. www.spars.com.

S/PDIF. Sony/Philips Digital Interface Format, a.k.a. IEC 958 Type II. A two-channel format developed by Sony and Philips for consumer use (though now commonly used for professional and semi-professional applications as well), intended for transmitting digital audio signals between pieces of gear. S/PDIF is very similar to the AES format, and, in general, the two formats are compatible (though cable adapters or a converter box may be required—be sure of what you need before you attempt to interconnect them). S/PDIF is carried over unbalanced coaxial cable, usually using RCA or occasionally BNC connectors, or fiber optic cable with TOSlink connectors. S/PDIF is designed to use 75-ohm cables, though regular audio RCA cables will also work. The S/PDIF specification supports resolution up to 20 bits, though some devices support 24-bit resolution over S/PDIF.

speaker. 1. Also known as driver. A transducer that converts electrical signals into sound waves. 2. Short for speaker cabinet.

speaker cabinet. An enclosure in which a speaker driver is mounted. The speaker cabinet is designed to prevent or manage interaction between the sound coming from the front of the speaker driver and the out-of-phase sound coming from the rear of the speaker driver. A variety of technologies and techniques are used in speaker cabinets to improve the efficiency, frequency response, and sound quality of the speaker, including ports, acoustic suspension designs, horns, and more.

Speakon^®. A multi-pin locking connector type developed by Neutrik for high-power applications, such as on power amplifiers and speakers. Speakon connectors are durable, reliable, and affordable; can handle high current levels; and offer the security of only inserting a jack in one way so no mistakes can be made. Two-, four-, and eight-conductor versions are available.

special effects. See effects.

specifications. Measurements of the performance of a product provided by the manufacturer. Because measuring techniques vary, and because measured data can be manipulated using different references and standards, specifications are only somewhat useful for comparing products and rating performance.

spectra. Plural of spectrum. The distribution of sound energy arranged by frequency.

spectral waterfall. See spectrogram.

spectrogram (a.k.a. sonogram, spectral waterfall, voiceprint). A three-dimensional visual representation of a spectrum, displaying changes in sound energy by frequency over time. See Figure S.15.

Figure S.15. A spectrogram displays changes in sound energy per frequency over time.

spectrum. 1. The range of frequencies comprising a waveform. Spectrum refers to the frequency-domain representation of the sound wave; a waveform display is a representation of the same information in the time domain.

spectrum analysis (a.k.a. frequency analysis, Fourier analysis). A mathematical method for analyzing the frequencies making up a sound wave.

speed of sound. The speed that sound waves travel through the air was first analyzed by Sir Isaac Newton. In fact, Newton came up with a figure of 979 feet per second, which is about 15 percent low. Pierre-Simon, Marquis de Laplace, a French mathematician, corrected the errors in Newton’s calculations. Through air, the speed of sound is approximately 1,130 feet per second, or 343 meters per second. (The exact figure varies depending on temperature, atmospheric conditions, and altitude.)

sphere stereo. A baffled stereo-miking technique using a pair of omnidirectional microphones mounted flush to, and separated by, an 8-inch solid sphere. The sphere is intended to simulate the acoustic properties of a human head, such as head shadow and ITD. The omnidirectional microphones maintain constant low-frequency response without proximity effect, regardless of distance from the source. Sphere stereo provides good imaging, separation, and depth, and natural sound quality. Sphere stereo differs from the “dummy head” technique, which is intended primarily for headphone listening, as it works well with speakers. See also baffled stereo.

spider mount. See shockmount.

spike. See power spike.

spill. See bleed.

SPL. See sound pressure level.

splice. 1. With analog recording, using a razorblade, splicing block, and splicing tape to edit together and join two pieces of tape. Typically, the two pieces of tape are cut at complementary angles so the splice will pass over the recorder’s playback head at an angle, helping to prevent a pop or click at the splice point. 2. With DAWs, editing together and joining two pieces of digital audio to create a new single piece of digital audio.

splicing block. A metal block, similar to a miter box used by a carpenter, used to precisely cut analog tape for splicing.

splicing tape. Adhesive tape used to splice together analog recording tape.

split. To divide a keyboard into two or more zones that each can transmit on a separate MIDI channel and/or play a different internal sound. See also split point.

split mixer. A type of mixer that has two input sections; one side is used for incoming signals from microphones and other sources, and the other section is used for signals returning from a multitrack tape recorder. See also in-line mixer.

split point. The point(s) at which a keyboard is divided into two or more separate zones. The split points define the key range of each zone. See also zone.

split stereo file. A stereo audio recording that is stored as two discrete files, one for the left channel and the other for the right channel. Split stereo files are preferred by some applications, such as Digide-sign Pro Tools. See also interleaved stereo audio.

SP-MIDI. Scalable Polyphony MIDI. An extension of the MIDI Specification for use in 3GPP mobile phones and handheld games, where different devices offer varying polyphony capabilities for playback of MIDI sequences. SP-MIDI allows the creators of sequences to specify MIDI channel priority (called channel masking) and note priority or MIP (Maximum Instantaneous Polyphony). SP-MIDI supports the GM2 soundset and limited MIDI continuous controllers.

SPL meter. A device that measures sound pressure level. An SPL meter is a useful tool for maintaining consistent (and safe) volume levels in the studio and for live performances.

spotting session. A meeting where a film’s music editor, director, and composer gather to decide what music will be used at what times in the film.

SPP. See Song Position Pointer.

spread. 1. The width of a stereo signal. 2. The time between two songs on an album. The spread is set during mastering and will vary depending on how the first song ends and the second song begins.

spring reverb. A simple type of mechanical reverb developed by the Hammond Organ company and released under the Accusonics brand name. An audio signal is sent into one end of a spring or springs and is picked up on the other end by a transducer. In addition to the signal transmitted straight through the spring, some signal is reflected and bounces back and forth in the spring. The reflections in the spring create a wash of sound, which serves as reverb. Spring reverbs are still widely used in guitar amplifiers.

sputtering. The process of applying a thin layer of metal to a surface. Sputtering is used to apply the extremely thin layer of gold to the surface of the Mylar diaphragm in microphones.

square wave. A type of cyclical waveform used for synthesis and other applications. Square waves contain a basic frequency, the fundamental, plus all of the odd integer harmonics. A clarinet produces a tone very close to a square wave. Square waves have two alternating states, high and low, making them useful for representing binary digital data. The ratio of the high state period to the total wave period is the duty cycle; a true square wave has a 50-percent duty cycle. Pulse Width Modulation (PWM) occurs when the wave’s duty cycle is modulated. See Figure S.16.

Figure S.16. A square wave contains a fundamental frequency plus all odd integer harmonics. The ratio of high state to overall period is the duty cycle.

S/s. Samples Per Second. A more accurate way of indicating sample rate. Using S/s reduces the possibility for misunderstanding whether kHz (the usual way of indicating sample rate) is referring to sample rate or a frequency.

stair stepping. The discrete values of a digital representation result in incremental stair-step changes rather than the smooth changes of analog (see Figure S.17). With digital audio signals, stair stepping results in quantization noise. With control or parameter changes, the result is zipper noise or audible steps as the parameter changes.

Figure S.17. The discrete values of a digital representation result in incremental stair-step changes rather than the smooth changes of analog.

standalone. 1. A hardware device that can operate by itself and does not depend on other gear to function. 2. A software program that runs directly in the operating system, as opposed to within a host program.

Standard MIDI File (a.k.a. SMF, .MID). A standard, “generic” file format designed to allow musicians on different computer platforms and/or using different sequencing programs to exchange sequence files. There are two types of Standard MIDI Files: Type 0, where all 16 MIDI channels are combined onto one multichannel track, and Type 1, where each of the 16 MIDI channels is stored on its own track. Both types preserve all channel settings and other information, so neither is really better than the other.

standby. A mode available on some devices, particularly guitar amplifiers and other tube-based items. Standby turns off various active features while maintaining power to components such as vacuum tubes.

standing waves. Sound waves reflecting between two parallel surfaces in a room. Standing waves always negatively impact the response of the room and are controlled using acoustic treatments. See also room mode.

star ground. A grounding scheme used to prevent ground loops. The ground is lifted from the AC electric power line of each piece of gear, then a new ground wire is run from the chassis of the item to the studio’s technical ground.

star network. A network built around a central device or hub. In audio, the most common example is using a master word clock generator with multiple outputs to synchronize all digital devices.

star quad. A type of balanced audio cable using four conductors—two for the positive signal and two for the negative signal—that are twisted into a spiral inside the cable’s shield. The doubled and twisted conductors help eliminate EMI and other interference problems.

start time. The time code point at which a sequencer or other device is set to begin playing or functioning. When the sequencer sees the start time arrive in the time code, it starts playing.

startup disk. The hard disk containing a computer’s operating system, used to boot up the system. With some computers, such as Macintoshes, you can have different operating systems on separate hard disks and designate which one to use as the startup disk when booting.

status byte. The part of a MIDI message that indicates what type of information the message carries, as well as the MIDI channel over which the message is being sent. There are eight message types: note on, note off, channel aftertouch, polyphonic aftertouch, continuous controller, pitch bend, program change, and system. (There are three types of system messages: System Common, System Real Time, and System Exclusive.)

STC. See Sound Transmission Class.

stem. A mono, stereo, or even surround submix of tracks from an audio production. The term comes from the film world, where separate stems are prepared of Foley, music, sound effects, dialogue, and other tracks. In music production, stems might be prepared of drums, bass, backing instruments, solos, lead vocals, and background vocals. The use of stems simplifies large, complex final mixdowns and allows overall processing to be applied to each stem separately. See also submix.

step. 1. Also known as whole step. In the standard Western equal temperament, the octave is divided into 12 equal-sized semitones or half steps of 100 cents each. A whole step comprises two semitones. 2. A discrete interval or increment.

step entry (a.k.a. step time). A mode, available in many sequencers, in which the MIDI data is entered while the sequencer is stopped. As each note or chord is played in, the sequencer automatically moves forward by a user-specified time increment. Step entry allows a composer or musician to enter much more complex or faster parts than he or she is capable of playing in real time, and to do so with perfect rhythmic accuracy.

stepped attenuator. A rotary control that has discrete switched steps to apply attenuation instead of a continuous potentiometer like a standard volume control. Stepped attenuators allow for accurate settings, as well as precise repeatability of settings.

stepped sine wave (a.k.a. modified sine wave). A digital representation of a sine wave, with stepped values instead of a smooth curve. Many UPS devices use stepped sine waves to drive an inverter to create their AC output power from a DC battery power source.

step sequencer. 1. An analog sequencer that plays back a series of voltages, set using a row of knobs, that can be used to create a note pattern or to change a parameter value, such as filter cutoff point. 2. A simple MIDI sequencer that plays back short note or parameter control patterns that are manually entered into a grid. The grid normally consists of one or two bars subdivided into sixteenth-note or other time increments. Step sequencers are found in drum machines, groove boxes, some DAWs, and in software applications such as Propellerhead Reason, and are most commonly used to create looping osti-nato patterns. See Figure S.18.

Figure S.18. Step sequencers play back a short looping pattern of notes or control changes.

step time. See step entry.

stereo. Short for stereophonic. 1. A signal comprising two channels of related audio material. 2. A multi-channel sound system that provides directional cues. The term has come to mean a two-channel system, but technically refers to any number of channels.

stereo bar. An accessory for mounting two microphones to a single stand. The mic mounts on stereo bars allow the mics to be turned/positioned for a variety of stereo miking techniques, such as XY stereo, ORTF, and others. See Figure S.19.

Figure S.19. A stereo bar is used to conveniently mount and position a pair of microphones for stereo recording.

stereo bus. A two-channel bus. See bus, aux send, stereo mix bus.

stereo imaging. See imaging.

stereo link. A switchable function that correlates the operation of two independent channels in a processor into true stereo channels. For example, when a two-channel compressor is stereo-linked, a signal crossing the threshold in either channel will trigger compression in both the left and right channels. This maintains stereo imaging as well as the integrity of the stereo field.

stereo microphone techniques. A number of microphone placement and configuration techniques designed to capture a stereo image of the source. Most stereo microphone techniques use two microphones, though some use more. The mics are arranged at particular distances apart and at certain angles relative to one another. Stereo miking offers a number of advantages over using a single mic: better depth, stereo width, more realistic ambience and imaging, and more. There are four basic approaches to stereo miking:

stereo mix bus (a.k.a. 2-bus). The main or master stereo output channels of a mixer, to which a mix of all the input channels, tape tracks, and returns is routed for final processing and level management.

stereophonic. See stereo.

stompbox (a.k.a. pedal). An audio processor mounted in a compact, floor-pedal format. Stomp-boxes have been most commonly used by guitarists and sometime bass players, but in recent years have made more frequent appearances in keyboard rigs and studios. Most stompboxes provide a single, basic processing function, such as distortion, delay, reverb, flanging, EQ, or filtering, though some modern processors are very versatile.

stop. See organ stop.

stopband. The range of frequencies processed (attenuated) by a filter. Some filters, such as bandpass filters, have more than one stopband. See also passband.

straight-wire. See uncolored.

streamer. In film scoring, a colored band that moves from left to right across the video screen followed by a circular flash. Streamers are used as cues for composers and conductors for where important musical “hits” should take place.

streaming. 1. A method for transmitting data in a continuous flow. A common example is providing continuously playing, or streaming, audio over the Internet, rather than offering a discrete file of the audio for download. 2. A technique for playing extremely large samples without loading them into the computer or sampler’s RAM.

streaming audio. Digital audio that is delivered as a continuous flow of data rather than as a complete file that must be downloaded or transferred. Streaming media will play back while the data is being transferred, rather than requiring that the entire file be transferred or downloaded before it can be played. See also streaming.

streaming media. Audio, video, and/or multimedia data that is transmitted over the Internet in streaming fashion by a server, received by the user’s computer, and displayed or played back in a player application.

stretch tuning. A technique used by piano tuners that tunes the high notes slightly sharp and the low notes slightly flat. The detuning is very minimal—a few cents at most—and is intended to make the high and low ranges sound more in tune to listener’s ears.

stripe. To record time code to analog tape so that multiple tape machines or other devices could be synchronized together. Striping is not necessary with digital systems, as the digital data maintains its own timing and synchronization reference that can be converted to time code if necessary.

striping. 1. See stripe. 2. A technique used in RAID 0 storage systems in which each piece of data is broken up into segments and written in round-robin fashion to the component hard drives of the RAID system. Striping RAIDs offer very fast performance for large files such as those found in video and some audio applications.

strip silence. A type of audio editing function found in DAWs that works similarly to noise gating: A threshold level is set, and any part of the audio in the track that falls below the threshold is silenced. The advantage of strip silence–type functions over noise gating is that strip silence breaks the track into separate audio regions or segments when it creates the silent areas, which can then be manipulated, processed, and edited separately. See Figure S.20.

Figure S.20. When a strip silence-type function is used, audio below a threshold level is removed, and the remaining audio is broken up into separate regions.

stuck note. A MIDI note that never receives a note off message and continues to sound after it should have ended. Stuck notes can occur if a MIDI cable is accidentally pulled out during a performance or playback, or from sequence editing errors or corrupted data, or for other reasons. Cures for stuck notes include sending an all notes off message, using a “panic button” command in a sequencer or keyboard, or turning off the power to the synth or sampler with the stuck note.

studio. 1. A room used for audio production. 2. A room where an artist or musician practices and works.

studio monitor. See reference monitor.

stutter effect (a.k.a. glitch). A DJ and remix effect created by copying a small slice of audio, then repeatedly pasting it into a track to achieve a stuttering effect. See Figure S.21.

Figure S.21. A stutter effect is created by repeatedly pasting a small slice of audio into a track. In this case, the first part of a word has been repeated, and a volume curve is used to fade it into the full word at the right.

stylus (a.k.a. needle). The component of a phonograph cartridge that reads the LP groove. A stylus has two parts: the cantilever and the tip. The cantilever is a short arm that holds the tip and mounts into the cartridge, while the tip is the part that actually sits in the record groove.

sub. See subwoofer.

subcode. Non-audio information that is written to digital tape. Subcode information might include track number, track length, elapsed track time, indexing, time code, and more.

subframe. A subdivision of an LTC frame. Typically, there are 80 or 100 subframes per frame.

subgroup. A number of channels or tracks in a mixer or DAW that are routed to a bus or a dedicated subgroup fader. Usually subgroups are created to make mixing easier. For example, all of the drum tracks or all of the backing vocals in a mix might be routed to a mono or stereo bus so their overall level can be controlled as a group using a single fader.

subharmonic. A frequency below the fundamental in a sound wave, usually at octave ratios of 1/2, 1/4, and so on, to the fundamental frequency. For example, a fundamental at 1,000 Hz might have subharmonics at 500 Hz, 250 Hz, 125 Hz, and so on. Some manufacturers have developed subharmonic “synthesizers” that can output subharmonic frequencies an octave or two below the fundamental based on the inputted sound. Subharmonic synthesizers are used to increase the amount of low end in a signal.

submenu. A menu in a computer program that branches out to open a second menu of related commands or selections. See Figure S.22.

Figure S.22. A submenu is a menu that branches off from a main menu and contains related commands.

submix. A number of tracks in a song that are mixed together through a bus, then mixed into the main mix. For example, all of the drum tracks or all of the backing vocals in a mix might be mixed to mono or stereo so their overall level can be controlled using a single fader and so they can be processed as a group. Submixes can also be used to organize a mix, to make mixing easier, or if there aren’t enough channels in the main mixer to handle all the signals. See also submixer.

submixer. A secondary mixer that creates a mono or stereo submix of signals that is then routed into the main mixer.

subsonic. Traveling at speeds slower than the speed of sound. Often incorrectly used in reference to frequencies below the range of human hearing. ( See also infrasonic.)

subtractive synthesis. A type of synthesis that starts with harmonically rich raw sounds, then uses filters to remove unwanted frequencies to achieve the desired final timbre. Most analog synthesizers use subtractive synthesis techniques.

subwoofer. A speaker dedicated to producing low-frequency sound waves, usually below 120 Hz.

sum and difference tones (a.k.a. combination tones). See difference tone, sum tone.

summing. In audio, mixing or combining signals together. The quality of the summing in a mixer has a great deal of impact on the sound quality of the mixes it creates.

summing box. An external analog hardware mixer that is designed to sum, or combine, the audio outputs from a DAW. The idea is to bypass the software mixer in the DAW and combine the track outputs externally in the analog domain. Summing boxes can range from very simple units with 8, 16, or more analog inputs (with no control over levels; levels are set in the DAW) and a single set of stereo outputs, to full-blown analog mixing consoles. Some engineers prefer to use summing boxes because they feel external analog summing provides superior performance to the built-in software digital mixers found in DAWs.

sum tone (a.k.a. combination tone). A frequency created under certain circumstances when two other frequencies are sounded together. The new frequency will be at the sum of the two original frequencies. For example, the sum tone created by two tones at 500 and 300 Hz would be at 800 Hz. See also difference tone.

supercardioid. A microphone polar pattern that is more directional than cardioid, and with a smaller rear lobe than hypercardioid. See Figure S.23.

Figure S.23. The supercardioid polar pattern is quite directional for good rejection of unwanted sound.

supersonic. Technically, traveling at speeds faster than the speed of sound. Sometimes incorrectly used to refer to frequencies above the range of human hearing. ( See also ultrasonic.)

supraaural. Headphones with cups that rest on the ear rather than on the side of the head surrounding the ear. Because they don’t seal around the ear, supraaural headphones generally do not provide good isolation from external sound or sound bleeding out of the headphones.

surface mount. Small electronic components that rest on, and are soldered to, the surface of a circuit board. (As opposed to traditional components that have legs that stick through holes in the circuit board and are soldered to the back of the board, after which the legs are trimmed off.) Surface-mount components save space and are easy for industrial assembly machines to handle, allowing much greater manufacturing efficiency. The tradeoff is that surface-mount boards are difficult to repair should a problem develop.

surge. See power surge.

surround. 1. The part of a speaker that connects the cone to the frame or basket. The surround is made from flexible material that allows the cone to move freely in response to the voice coil, but must be stable enough to keep the voice coil centered around the magnet. 2. See surround sound.

surround panner. 1. A software control used to position a sound in a surround field. Surround panners can position mono, stereo, or even surround tracks in the surround field and may include additional controls, such as a feed for sending low frequencies from the signal to the system’s subwoofer or LFE channel, a “divergence” control for setting the amount of the front left/right portion of the signal that is also fed to the center channel, and more. Some surround panners are modeled after a joystick, where one control is used to set the panning; others use separate controls for setting the side-to-side panning and the front-to-back panning. Most surround panners also allow the channel’s feeds to the various speakers to be muted or soloed. 2. A hardware control box that controls a software surround panner.

surround sound. A multichannel sound reproduction system with more than two channels of related audio material. Typical formats include 5.1 (five main speakers with one subwoofer) and 7.1 (seven main speakers plus one subwoofer). Originally intended for film sound, surround sound has also made inroads into music playback with DVD-Audio, SACD, and video sound.

suspension mount. See shockmount.

sustain. 1. The stage in an envelope generator that determines how long a note or parameter value will be held. 2. The duration of a musical note.

sustained transfer rate. A specification measuring how fast a drive can send and receive data. Sustained transfer rate is impacted by system processing delays, the time required for head switching, seek time, and more factors. Sustained transfer rate is one of the most useful specs for evaluating how a drive will perform for audio or video applications.

sustain pedal. 1. The rightmost pedal on a piano, which lifts the dampers off all the strings and allows the notes to continue to ring, even if the keys that played them are released. 2. MIDI Continuous Controller #64. The MIDI sustain controller turns on with a MIDI value of 127, off with a MIDI value of 0, and (unless remapped by the user) performs the same function as a piano’s sustain pedal by holding any active envelope generators at the sustain stage so the notes continue to sound. (Whether a note continues to sound when held by CC #64 also depends on the polyphony of the sound generator. If there is not enough polyphony to support all the sustained notes, some will be cut off.)

SVGA. Super Video Graphics Array. An enhanced version of the VGA video protocol that can display up to 16.7 million colors with resolutions up to 1,280 × 1,024 pixels.

sweep (a.k.a. frequency sweep). Continuous playback of a tone smoothly increasing or decreasing in frequency. Sweeps are used for a variety of test and analysis purposes.

sweepable mids. An equalizer where the center frequency and amount of boost/cut in a midrange band can be controlled (see Figure S.24). Generally bandwidth can’t be controlled in a sweepable-mid EQ, and the high- and low-frequency bands are fixed in frequency. See also quasi-parametric.

Figure S.24. The channel EQ found in many mixers offers sweepable mids—a midrange band that has control over the boost/cut amount and frequency.

sweetening (a.k.a. post-production). Sweetening is a video term for adding music, sound effects, and other audio to a film. The term has been adopted in music production for adding effects to an audio track or mix.

sweet spot. The location in a listening room with the best response and imaging. For stereo, this is normally the third point in an equilateral triangle with the two monitors. Finding the sweet spot in a studio control room is essential for accurate monitoring and for making solid decisions about the quality of a mix or recording.

swing. 1. A jazz-like rhythmic feel, where the first of a pair of eighth-notes is played longer than the second. 2. A quantization function in sequencers and DAWs that adds an adjustable amount of swing feel to consecutive MIDI eighth notes in an attempt to make the sequence sound and feel more human. Usually the swing parameter is set as a percentage, from 0% (no swing) to 100% (heavy swing).

switching power supply. A type of AC power supply that switches current into a transformer at very high rates, above audio frequencies. The transformers in switching power supplies are lighter, smaller, and less expensive than those in regular “linear” power supplies. Some switching power supplies can also regulate the voltage better than linear supplies.

sympathetic vibration. Vibrations of a particular frequency produced in a material as a result of contact with sound waves of that same frequency. An increase in the volume of the sound caused by the sympathetic vibration is called resonance.

sync. Short for synchronize.

Sync 24 (a.k.a. DIN Sync). A type of synchronization developed by Roland for older drum machines and other devices, such as the TR-808, TR-909, TB-303, and MC-202. Sync 24 used a 5-pin DIN connector similar to the one later used for MIDI (though the two are not directly compatible) and carried start and stop messages as well as a 24 PPQN timing clock stream. Sync 24 was made obsolete by MIDI.

synchronization. See synchronize.

synchronize. 1. To connect two or more devices together so that they operate as one unit. 2. To set up one unit to follow the timing of a second unit. 3. To lock together the clocks in digital audio devices.

synchronized delay. An echo effect that is synchronized to the tempo of the song. This allows delays to be set to rhythmic values.

synchronizer. 1. A hardware device that handles the synchronization of two or more analog tape machines. Synchronizers do this by comparing the time code coming from the tape machines with reference time code and adjusting the speed of the tape machines to keep them locked together. 2. A hardware device that reads LTC or VITC and synchronizes other devices to that time code.

synchronous. Events that are coordinated in time, often by a synchronization clock. Some synchronous data transfers, such as those handled by S/PDIF, AES, and other digital formats, do not require handshaking or other confirmation to verify that the transferred information has arrived, while others do require responses in order to stay synchronized.

synth. Short for synthesizer.

synth action. A type of unweighted plastic keyboard action that does not attempt to emulate the resistance and feel of an acoustic piano. Typically found on 61-note and shorter keyboards, synth actions use springs instead of weights or hammer mechanisms and are less expensive than other types of actions. Synth action allows for fast playing and may work better for certain sorts of sounds (such as synthesizer leads) than a weighted action. See also action.

synthesizer. An electronic musical instrument that can generate waveforms using oscillators. These waveforms can then be combined, manipulated, filtered, and otherwise processed to create musically useful timbres. There are a wide range of different types of synthesis, all of which have their individual strengths and weaknesses when producing certain types of sounds. A few of these include:

SyQuest. An obsolete removable disk storage format developed by SyQuest, later purchased by Iomega.

Sys Ex. See System Exclusive.

Sys Ex dump. Transferring the RAM contents of a synthesizer or other MIDI-compatible device using System Exclusive messages.

system bus (a.k.a. frontside bus). The data bus in a computer that connects the CPU to the RAM.

System Common message. A type of MIDI system message that is intended for the entire MIDI network. System Common messages include MIDI Time Code Quarter Frame, Song Position Pointer, Song Select, Tuning Request, and EOX (End of System Exclusive).

System Exclusive. A type of MIDI system message compatible with one specific piece of gear. System Exclusive messages are used to carry proprietary control information, to control parameters that can’t be accessed with continuous controller messages, and to transfer RAM program data between synthesizers and other MIDI-compatible gear. System Exclusive messages allow editor/librarian software running on computers to display, take control of, and edit the parameters of a MIDI-compatible device.

system preferences. A preference file that contains settings for a computer’s operating system. See also preferences.

System Real-Time message. A type of MIDI system message that addresses timing, sequence playback, or synchronization. System Real-Time messages include MIDI Timing Clock, Start, Stop, Continue, Active Sensing, and System Reset.

System Reset. A MIDI System Real-Time message that tells any receiving device to reset all its controls to their default position. The exact effect of a System Reset message will depend on how the receiving device is programmed to respond.