Glossary of Audio, Recording
and Music Terms "S"
Safe – A setting on an analog multitrack tape recorder that will prevent a track from recording when the record button is pressed.
Sample – 1) In digital recording, the numerical measure of the level of a waveform at a given instant of time. Analog music is represented digitally by many samples taken in rapid succession. 2) A short segment of audio recorded for the purpose of reproducing and manipulating the sound digitally.
Sample Dump Standard (SDS) – See “MIDI Sample Dump Standard.”
Sample Rate – In digital recording, the number of times per second that samples are taken. The higher the sample rate, the more realistic the digital reproduction of the sound, and the higher frequencies of the sound can be reproduced. In digital audio, the quality and resolution of a digitally reproduced sound are described as a combination of sample rate and bitrate. (See also “Bitrate.”)
Sample Rate Conversion – The conversion of digital audio taken at one sample rate to a different sample rate without first converting the signal to analog.
Sampler – A device that records and plays samples, often with features for editing, manipulating and storing the samples.
Saturation – 1) The point at which magnetic tape reaches full magnetization due to an excess of sound level. This creates some distortion that some audiophiles describe as “analog warmth” a desirable quality in certain instances. 2) The audio distortion that occurs by overdriving a signal through a tube amplifier or preamp—again producing color and warmth in the sound that engineers often find appealing. 3) A digital plugin that emulates tape or tube saturation.
Sawtooth Wave – A waveform that jumps from a zero value to a peak value and then immediately drops to a zero value for each cycle. (Sometimes also called “Ramp Wave.”)
Scratch – 1) A descriptive term meaning “temporary”. 2) A scratch vocal is a vocal done during a basic recording session to help the musicians play their parts. At a later date the final vocal track is overdubbed. 3) The action of a musician or disc jockey quickly moving a record back and forth on a turntable reproducing the stylus motion to create a rhythm pattern of sound.
Scrubbing – The action or function of shuttling a piece of recorded audio back and forth while monitoring it, typically to locate a certain point in the recording. In earlier days, scrubbing was done with reel-to-reel analog tape by manually turning the reels to pull the tape across the playhead. Today, scrubbing is primarily done digitally on a DAW by dragging the cursor back and forth across the waveform.
Second Engineer – An assistant recording engineer.
Send – See “Auxiliary Send.”
Send Level – A control determining the signal level sent to a send bus.
Sensitivity – 1) In audio settings, describes the amount of output that a microphone can produce from a standard level of sound, as compared to the output of another microphone from the same sound level. 2) In music, describes the artistic persona in general.
Sequence – 1) A pre-programmed set of musical events, such as pitches, sounding of samples, and rests, to be played in order by a device. Also refers to the action of programming the device to play this set of musical events. 2) Loosely referring to a segment of music in general.
Sequencer – A computerized device or software that can be programmed to play a stepped order of musical events, including playing of pitches, sounding of samples, and rests.
Serial Data – A digital data stream where individual bits are transmitted one after another over a single connection (as opposed to “parallel data,” in which multiple bits can be sent at once). Most data connections in the recording studio transmit serial data—for example, USB, Firewire and MIDI.
Series Connection – Connecting devices (especially circuit elements) so that the electrical signal flows from one thing to the next, to the next, etc.
Set Up – The positioning of microphones, instruments, connections and monitoring in the studio, as well as the controls and levels on consoles, DAWs, etc., in preparation for recording.
Shelf – A frequency response of an equalization circuit where the boost or cut of frequencies forms a shelf on a frequency response graph. A high-frequency shelf control affects signal levels at the set frequency and all frequencies above it; a low-frequency shelf does the same for signals at and below the set frequency.
Shelf Filter – A name for the circuit in an equalizer used to obtain the shelf.
Shield – The outer conductive wrapping around an inner wire or wires in a cable, for the purpose of shielding the cable from picking up external electromagnetic interference.
Shielded Cable – Cable that has a shield around an inner conductor or inner conductors.
Shock Mount – An elastic mount on microphone stand that reduces the impact of unwanted vibrations that may affect the stand (for example, floor vibrations from footsteps).
Short (Short Circuit) – A direct connection between two points in a circuit that (usually) should not be connected.
Short Delay – Delay times under 20 milliseconds.
Shortest Path – A technique in recording that routes the signal through the least amount of active (amplified) devices during recording.
Shotgun Microphone – A microphone with a long line filter, a tube that acoustically cancels sound arriving from the side, to make the microphone pick up much better in one direction than in any other direction. This gives the shotgun mic a tight, hypercardioid pickup pattern. Shotgun microphones are commonly used to record dialogue in filming situations, usually held on a boom stand with a shock mount.
Sibilance – Energy from a voice centered around 7 kHz, caused by pronouncing “s”, “sh” or “ch” sounds.
Sidechain – An auxiliary input to a signal processor that allows control of the processing to be triggered by an external source. A common use of sidechaining is in compressors, particularly in ducking effects where the presence of a particular audio signal triggers the compression of another audio signal. (See also “Ducking.”)
Signal – 1) In audio, an alternating current (or voltage) matching the waveform of, or being originally obtained from, a sound pressure wave. 2) Also in audio, an alternating current (or voltage) between 20 Hz and 20,000 Hz. 3) A digital audio bit stream.
Signal Flow – 1) In the general sense, the path that an audio signal travels from the sound source to the system output. (For example, from the vocalist’s voice into the microphone, through the cables, into the preamp, out of the preamp into the console, through all inserts and buses, and output into the DAW for recording.) 2) Signal flow is often specifically meant to refer to the routing of an audio signal through the console, from input to output.
Signal Processing – The practice of altering the character or sound of an audio signal through a variety of devices or plug-ins, such as equalizers, compressors, reverb units, etc.
Signal-to-Noise Ratio (SNR) – The comparison of the strength of a signal level to the amount of noise emitted by the device, expressed in dB.
Sine Wave – The waveform of a “pure tone”—a sound vibrating at a single frequency. Depicted graphically, a sine wave is a smooth, oscillating curve.
Slap Echo – (Also called Slapback) A single, distinct echo of a sound, which can result naturally from higher frequencies reflecting off a non-absorbent wall, or artificially reproduced by a signal processing unit or plugin. Slap echo creates a “live” sounding effect similar to what you would hear in an arena.
Slate (Slating) – 1) In video/film, the identification of a scene and take at the beginning of the clip for the purpose of video editing. This is done by presenting the scene/take in written form in front of the camera on a clapboard, calling the scene/take verbally, then marking it audibly with the clapper for the purpose of syncing audio to the video. 2) In audio recording, the similar practice of identifying a take of music by an audible cue at the beginning of the recorded track. While some engineers still practice this, it was more necessary in the days of analog tape recording because it helped editors keep track of the location of takes on the recorder. Today, DAWs make it easier to keep track by identifying each take visually on the screen.
Slave – 1) In audio, any device which syncs to another device by reading the clock information emitted by the master device. 2) In MIDI, any device or instrument that is being operated remotely by MIDI information sent from another device.
Smart FSK – An updated form of Frequency-Shift Key (FSK) sync that enables MIDI devices to sync to analog tape recorders and/or other recording devices. A digital signal with MIDI Song Position Pointer (SPP) data is encoded onto a spare track, which identifies the exact bar, measure and beat for MIDI sequencers/devices at any point in the recording. This enables the device to start playing at exactly the right place and tempo no matter where you start the tape. (See also “Frequency-Shift Key.”)
SMPTE – 1) Abbreviation for Society of Motion Picture and Television Engineers. 2) See “SMPTE Time Code.”
SMPTE Time Code – (Abbreviated “SMPTE“) A standardized timing and sync signal protocol created by the Society of Motion Picture and Television Engineers for the purpose of syncing audio to video/film, which can also be used for syncing purposes in audio recording environments. Many audio professionals simply refer to this time code as “SMPTE.”
Snare – 1) Abbreviation for “snare drum.” 2) The metal strands stretched across the bottom head of a snare drum, which help produce the piercing “cracking” sound when the snare drum is struck.
Sock Cymbal – A rarely used alternate term for “hi-hat,” left over from the days when hi-hat cymbals were placed at “sock level.” (See also “Hi-Hat.”)
Soft Knee – In compression, refers to the gradual introduction of compression of the signal once the sound level crosses the threshold. (See also “Knee.”)
Software Instrument – See “Virtual Instrument.”
Soldering – The action of making connections with solder, a soft metal alloy that is used to bond two metal surfaces by melting. In audio settings, soldering is used for a variety of purposes in building, modifying or repairing gear—perhaps most often to repair or build audio cables as a cost-saving effort, as opposed to buying new ones or sending them off for repair.
Solid State – In electronics, refers to the use of transistors and semiconductors (solid materials) in the building of electronic devices, as opposed to tubes. In the recording studio, solid state amplifiers have different properties than tube amps, and each has its own advantages and disadvantages. A more recent application of solid state construction is in computer devices, particularly solid state hard drives (SSD), which transfer data more quickly than conventional spinning disc drives, and are less prone to breakage.
Solo – 1) A circuit in a console or DAW that allows one or more selected channels to be heard or to reach the output, while other channels are automatically muted. 2) In music, a segment of a song in which a vocalist or instrument is featured above other instruments.
Solo Switch – A switch that activates the solo function on a console or DAW.
Song Position Pointer (SPP) – A MIDI message that enables connected MIDI devices to locate a given point in the song. Used in conjunction with MIDI clock as a way of synchronizing devices or telling a connected device when to begin playing.
Sound Blanket – A thick blanket that can be put on floors or hung to add sound absorption to the room, and help prevent sound reflections.
Sound Effects (SFX) – Sounds other than dialogue, narration or music that are added to audio, usually in the context of film/video.
Sound File – A digital audio recording that can be stored in a computer or on a digital storage medium (such as a hard disk).
Sound Level – See “Sound Pressure Level.”
Sound Module – An electronic instrument (tone generator, synth or sampler playback unit) that has no playable interface, but instead responds to incoming MIDI message. Often sound modules were created as the “brains” of popular synthesizers, cheaper versions of the product that could be added to an existing MIDI configuration. Today, sound modules can also occur as software versions or plugins to be accessed on a computer.
Sound Pressure Level (SPL) – In scientific/technical terms, the measure of the change in air pressure caused by a sound wave, measured in dB. We hear and perceive SPL in terms of amplitude, volume or loudness of the sound.
Sound Source – The origin of a sound, whose vibrations create sound waves.
Soundtrack – 1) Broadly speaking, refers to any/all audio that accompanies an instance of visual media, whether music, dialogue or SFX. 2) In more common terms, refers to the musical score and/or licensed music synced to a film, video, TV program or video game.
Sound Wave – (Also called “Sound Pressure Wave”) A wave caused by a vibration that results in slight variations in air pressure, which we hear as sound.
Spaced Pair – (Also called “A/B Technique“) A stereo microphone placement technique in which two cardioid or omnidirectional microphones are spaced somewhere between 3-10 feet apart from each other (depending on the size of the sound source) to create a left/right stereo image.
S/PDIF – Abbreviation for “Sony/Phillips Digital Interface,” a protocol for sending and receiving digital audio signals using a common RCA connector.
Speaker – A device that converts electrical signals to sound; more technically, a transducer that changes an electrical audio signal into sound pressure waves.
Speed of Sound – Generally speaking, the time it takes for a sound wave to travel through a medium. Sound travels at different speeds through solids, liquids and gases, and though we usually think of sound as traveling through the air, differences in temperature, air pressure and humidity can also affect how fast sound travels. For a starting frame of reference, the speed of sound is generally defined by aerospace engineers as “Mach 1.0,” translating to 340.29 meters per second (approx. 761.1 mph, or 1116 feet per second), which is how fast sound travels through the air at sea level at a temperature of 15 degrees Celsius (59 degrees Fahrenheit). By contrast, at 70 degrees Fahrenheit under standard atmospheric conditions, the speed of sound is about 344 m/s, or 770 mph. (See how complicated it can get?)
SPL – See “Sound Pressure Level.”
Splicing – Historically, the act of attaching previously cut pieces of audio tape or film in precise locations by applying a special kind of adhesive tape on the back. This is/was done for the purpose of shortening sections of audio or editing film. Today, splicing has become a very simple process by editing sections of audio or video digitally with a DAW or film editing software.
Spring Reverb – A device that simulates reverberation by creating vibrations within a metal spring by attaching it to a transducer and sending the audio signal through it. A pickup at the other end converts those vibrations into an electrical signal which is mixed with the original audio signal. While the physical spring reverbs still exist, most studios emulate spring reverb with the use of plug-ins or hardware reverb units.
Square Wave – A wave shape in which the voltage rises instantly to one level, stays at that level for a time, instantly falls to another level and stays at that level, and finally instantly rises to its original level to complete the wave cycle.
Safety Take (ST) – An additional take of audio captured for good measure after a take of acceptable quality has been recorded.
Stage – 1) The partially enclosed or raised area where live musicians perform. 2) In reverberation effects devices, an echo added before the reverberation to simulate echoes that would come from a concert stage.
Stage Monitor – A speaker on the stage that enables performers to hear themselves and to hear what the other musicians are playing on stage.
Standard Operating Level – A reference voltage level or maximum average level that should not be exceeded in normal operation.
Standing Wave – An unwanted sound wave pattern that often occurs when the sound wave bounces between two reflective parallel surfaces in a room, and the reflected waves interfere with the initial wave coming from the sound source, in which the combined wavelength of the affected frequency is effectively the length of the room. This creates the audible illusion that the wave is standing still, so the frequency is amplified to an unwanted level in certain parts of the room while nearly absent in others. Standing waves are most common in square or rectangular rooms with parallel surfaces, so acoustic designers try to prevent these waves by installing absorptive materials or introducing other items to offset the parallel surfaces.
Step Mode – A setting in a sequencer or DAW in which notes are input manually, one note or step at a time.
Stereo – A recording or reproduction of at least two channels where positioning of instrument sounds left to right can be perceived.
Stereo Image – The audible perception of stereo, in which different sounds sources appear to be coming from far left, far right or any place in between.
Stereo Micing – Placement of two or more mics so that their outputs combine to create a stereo image.
Strike – To put away equipment and clean up after a recording session.
Subcode – Additional information bits that are recorded alongside digital audio, used for control and playback purposes.
Subframe – A unit smaller than one frame in SMPTE time code.
Subgroup – A number of input channels on a console that can be controlled and adjusted as a single set before sending the combined signal to the master output. Sometimes also called “Submix,” “Bus” or just “Group.”
Submaster/Sub-Master – The fader which controls the combined level of sound from several channels during mixdown or recording.
Submix – See “Subgroup.”
Subtractive Synthesis – An old-school method of sound synthesis in which sounds are designed and created by generating harmonically rich waveforms, then filtering out unwanted harmonics to arrive at the desired sound.
Sum – A signal that is the mix of the two stereo channels at equal level and in phase.
Summing – The process of blending two or more signals into one mixed signal. In summing audio, each successive channel adds volume to the overall signal, so channels must be mixed in order to prevent peaking the combined signal.
Super-Cardioid Pattern – A very tight cardioid microphone pattern with maximum sensitivity on axis and the least amount of sensitivity approximately 150 degrees off-axis.
Surround Sound – A technique of recording and playback in which the listener hears various aspects of the sound from front to back as well as side-to-side—a 360-degree audio image, as opposed to the standard stereo left-right image. Surround sound can occur in various formats with different numbers of speakers arrayed through the room. Surround sound today is most commonly used in film and TV production.
Sustain – The third of the four stages of a sound (Attack, Decay, Sustain and Release, or the ADSR envelope), the sustain is the part of the sound that holds at approximately the same volume after the initial attack and drop in volume level (decay), until the sound stops playing. In some instruments, sustain is short or virtually nonexistent; in many instruments, sustain loses volume over time until the sound dies off (for example, in a held piano note). In synthesizers and samplers, the sustain function can be set to hold the note at the same volume level indefinitely until the key is released.
Sweetening – A vague term referring to the fine-tuning of audio in the post-production stage of recording. Effectively, any small “tweaks” to to make the audio sound better is considered sweetening.
Switch – A device that makes and/or breaks electrical connections.
Switchable Pattern Microphone – A microphone having the capability of two or more pickup patterns, which can be toggled by use of a switch on the microphone.
Sync – Short for “Synchronization.” In audio/studio settings, sync refers to the correlating of two or more pieces of audio or video in relation to each other. This can include syncing two recording/playback devices timed to a sync signal like SMPTE Time Code, synchronizing audio with video in film or TV, and many other examples. Licensing a song or piece of music for placement in film, TV or video is also referred to as “syncing.”
Sync Pop – A short tone (usually a sine wave at 1 kHz, and the length of a frame of film) that is placed exactly two seconds before the start of a piece of film or music. The sync pop is used to make sure that all related audio and video tracks stay in sync with each other through all stages of post-production.
Synthesizer – A musical instrument that uses electrical oscillators to generate tones artificially, either to simulate the sounds of other instruments or to create other sounds not possible with other instruments.
System Exclusive (SysEx) – A MIDI message that will only be recognized by a unit of a particular manufacturer.