Signal-to-Noise Ratio, S/N Ratio@The proportion between the audio signal level being produced by an electronic audio device, and the inherent, constant noise level which the device itself adds to the signal. In other words, the higher the maximum S/N ratio permitted by a system, the greater its useful Dynamic Range. The sound is cleaner, because there is less background noise. For digital audio systems, a more fundamental issue is Signal-to-Error ratio or S/E, where the level of Quantization Error is inversely proportional to the number of bits per sample (also known as Quantization Noise). To determine a theoretical signal-to-error ratio for a given Bit-Depth, multiply the number of bits by 6.02dB, then add 1.76dB to the result. Thus, 16-bit digital audio systems would theoretically be capable of 98.08dB signal-to-error ratio, if they were not subject to other design limitations in the physical hardware itself. See also Quantization, Quantization Error, Digital.@SIMM@Single In-Line Memory Module, a small circuit board containing RAM memory chips. SIMMs can be easily installed in a special socket on the computer's main logic board (also on some other computer cards and synthesizers/samplers). For Macintosh computers, there are various common types of SIMMs, 30-pin (the original standard SIMM; it was used on Mac models through the Mac II and LCII series, and the Quadra 950), and 72-pin (Macintosh models Quadra 650, 800, 840av, 660av, 605/610/630, some later models of the Performa 400 and 600 series and all 500 series, Performa 5000 and 6000 series, Centris, LCIII, PowerMac 6100, 7100, 8100). The Mac IIfx alone used a unique, 64-pin SIMM module. Newer Power Mac models since 1995 (7000, 8000, 9000 series, and G3)have begun to use DIMM modules, see definition. See also RAM, DIMM.@Sine Wave@A type of basic audio waveform, which consists only of a fundamental tone, with no harmonics above it, i.e., a single frequency, periodic oscillation.@Slap Echo, Flutter Echo@Slap echo is a bright, delayed repetition of an input signal, separated by an interval long enough to be perceived separately from the original sound (usually in the range of 50 to 125 milliseconds). Similar to the effect of sound being reflected back from reflective walls at a certain distance from the source, with little high-frequency attenuation. For practical examples, listen to the lead vocal on any rockabilly recording! Also sometimes referred to as slapback. Flutter Echo consists of multiple repetitions at a similar time interval. It is an undesirable effect, typically produced by the presence of two parallel surfaces in a room with insufficient sound absorption. See also Delay, Echo.@Slate@A spoken identification of the song, take, etc., recorded directly onto the original master tape, typically from a Talkback microphone input on the mixing console which has been fed to all tape outputs. The name derives from the chalkboard slates once used in films for this same identifying purpose (with a clapstick along the top.) The slate function of recording consoles typically also outputs a low-frequency tone (e.g. 30 Hz), which aids in locating the beginning of a song or take when the tape transport is in rewind or fast forward.@Slave Clock@A connection for synchronizing the sample rate of a digital device to another external clock source, for example the 256x "SuperClock" used for Digidesign interfaces and the SMPTE Slave Driver. See also Word Sync.@Slip Mode@One of the four basic editing modes of the Pro Tools Edit Window, activated by clicking the Slip button. In this mode, Regions can be moved about freely, without snapping to other Regions as they do in Shuffle mode. Regions can be dragged anywhere within a Track, or even placed so that they overlap other existing Regions. Unlike Shuffle mode, placing Regions into Tracks while in Slip mode doesnÕt shuffle aside subsequent regions. See also Shuffle Mode, Spot Mode, Grid Mode.@Slope@A characteristic of filters. The rate at which frequencies are progressively more attenuated (or boosted) at greater distances from a given frequency (such as the Cutoff Frequency, Center Frequency, or Shelving frequency). The slopes of filters are described in dB per octave; higher values correspond to steeper slopes. The Q, or Quality Factor, describes the slope of a Peaking filter. See also Lowpass Filter, Cutoff Frequency, Q, Peaking Filter.@SMDI, SCSI MIDI Device Interface@A standard protocol for transferring sampled digital audio between SCSI-equipped samplers and personal computers. SMDI achieves velocities up to 300 times faster than sample transfers via SDS, the MIDI-based Sample Dump Standard. See also SCSI.@SMPTE Slave Driver, SSD@Digidesign product. A high-quality SMPTE-MTC synchronizer, with sample clock (word sync) reference for Pro Tools audio interfaces. Synchronization requirements for digital audio are more rigorous than analog. Along with the relatively coarse time reference provided by SMPTE, for demanding applications (such as audio post) highly stable, continuous re-synchronization of the internal clocks of the digital recorders is required in order to avoid drift, maintaining accurate sync over long periods of time. The SSD also supports "pull-down/up" sample rates for film-video conversions. Features of the SSD are now incorporated into Digidesign's Universal Slave Driver (USD). See also SMPTE, MTC, Word Sync.@SMPTE Timecode, SMPTE/EBU@An industry-standard method of encoding an absolute time reference into an 80-bit data word. A digital code which identifies each frame with a unique address, reserving unassigned "user" bits within the data word, to be used for other purposes. SMPTE timecode is used for synchronizing sound to film/video, MIDI sequencers, DAWs and other devices to a multitrack recorder or video master. Formally adopted by the SMPTE and EBU in 1972 (SMPTE 12M, IEC 461, ISO 9642). The numerical format consists of hours, minutes, seconds, frames (and sometimes subframes). The number of frames per second (fps) can be 24, 25, 29.97 or 30 (with a "drop-frame" variant, used for NTSC video only). There are three mediums for the encoding of SMPTE timecode information: LTC (Longitudinal TimeCode) is the most common type, where an audio signal encodes the time data through biphase modulation; VITC (Vertical Interval TimeCode), incorporates the data into a video signal, in the overscan area at the top of each video frame, and MTC (MIDI TimeCode) conveys the SMPTE information as MIDI data. See also LTC, VITC, MTC, Striping.@Snap@MIDI sequencing, audio editor term. A function which automatically adjusts segments of audio or MIDI which have been dragged by the user, to some specified subdivision of the musical beat (for example, to the nearest 1/16 note). Many DAWs provide this option for "snapping" audio regions to other time units, such as frames, 100-millisecond increments, etc.). Comparable to the "snap to grid" option in graphics programs.@Snapshot@A type of audio mixing console automation, where a given, static state of the mixer can be memorized. Useful for recalling previous settings. Some mixer automation systems also permit stringing together these "snapshots", specifying transition times between them, to achieve a kind of automated mixdown. "Snapshot-based" automation methods can also be useful even in systems like Pro Tools, which incorporate full dynamic automation of mixer controls in real time. Also known as "mixer states".@SND Resource@Apple Macintosh term. A data format for digitized sound, commonly used for system "Beeps" (alert sounds) and also for sounds incorporated into Hypercard stacks (Format 1) and all other programs (Format 2). Unlike other sound file formats (AIFF, SDII, .WAV), SND audio data is a "Resource", an area of data WITHIN another file. For this reason, when you choose the "snd Resource" option in the "Save As" dialog of Sound Designer, you will first be prompted to specify a "resource" name, before indicating the name of an existing file into which this sound resource will be incorporated.@Software@The programs, or instructions, in a computer system (or any other device controlled by a digital processor), as opposed to the actual mechanical and electrical components (the hardware) that physically make up the system.@Solo@A button on each track of a mixing console, or a similar construct in mixing software, which mutes all audio tracks except the one(s) being soloed. Useful for isolating that instrument's sound in order to make adjustments to input gain, EQ, and so on. On some mixers, a track can be soloed without necessarily affecting the performer's headphone mix (cue mix), house mix, etc. The Solo function usually permits hearing the Pre-Fader Level (PFL), a separate volume control is provided to adjust the overall Solo monitoring level. See also PFL, Mute.@Song Position Pointer, SPP@A type of System Common MIDI message, often used along with MIDI Clock to synchronize MIDI sequencers to tape (or each other). Indicates the current location within a MIDI sequence in bars, beats and sixteenth (1/16) notes. In this way, when the sync master (an interface reading a Smart FSK signal from tape, or another MIDI sequencer sending these messages over MIDI) starts sending a synchronization signal from some point within a song, the receiving device can calculate the correct point from where it should commence playback. Also abbreviated SPP.@Sony 9-pin@A protocol developed by Sony for serial control of VTRs (video tape recorders), which has become a de facto industry standard for remote control and synchronization of their transport functions.@Sound Accelerator II@Digidesign product. A Macintosh NuBus computer card that forms part of the Sound Tools II hard-disk based audio recording and editing system. A SCSI-50 cable connects this card to the 442 external audio interface. The Sound Accelerator (1) card corresponded to the original Sound Tools (1) system, and was in fact the original Digidesign card (since it was sold as an add-on for Sound Designer users, and was later bundled into Sound Tools II hard-disk recording/editing systems. See Sound Tools II, Sound Designer II.@Sound Designer II@Digidesign product. Industry-standard stereo/mono digital audio editing/recording software that supported Audiomedia, Sound Tools, Pro Tools, ProMaster 20, and Session 8 Macintosh systems. Digital audio editing, DSP functions (both destructive and realtime) included parametric & graphic EQ, dynamics processing. Gain change, normalization, mixing and merging separate audio files, fade in/out, crossfades, pitch shift, time compression & expansion, reverse, invert phase. Non-linear playlist editing for mastering and music editing applications. Registered users received free DATa software, for backup of sound data to DAT machines through digital port, and MasterList, for sequencing multiple files during the preparation of masters. Open architecture permitted installing numerous 3rd party plug-in effects - the first digital audio program to implement an open plug-in architecture.@Sound Forge@A professional, Windows-based sound editing and processing program, including transfers to various samplers, developed by Sonic Foundry.@Sound Manager@A Macintosh operating system extension created by Apple, to facilitate the playback and recording of digital audio at different sample rates and bit depths. Sound Manager version 3 and greater handles real-time conversion of 16-bit or stereo sound files to 8-bit or mono for Macintosh models with these limitations. Sound Manager also improve playback quality when QuickTime movies which include audio tracks are reproduced through the Mac's internal sound hardware, as it takes over the sound playback responsibility from QuickTime itself.@Sound Tools II@Hard disk audio recording and editing system for Macintosh, with the same external 442 audio interface as Pro Tools I, plus the Sound Accelerator II NuBus card. Includes Sound Designer II stereo editing/DSP software, compatible with all plug-ins, including Digidesign Intelligent Noise Reduction (DINR). High-quality digital recording (93db s/n), with four balanced XLR line-level ins/outs at +4dBm. AES/EBU and S/PDIF digital ins/outs. Up to four independent channels of record/playback when used with digital audio versions of several MIDI sequencers, Session or Deck. Its predecessor, Sound Tools (I), featured the Sound Accelerator I card and the AD/IN analog interface and/or the DAT I/O digital interface, 1/2 rack each. (A high-quality balanced analog interface, the Pro I/O, was also available.)@Sound Tools ProMaster 20@Digidesign product. Ultra-high fidelity version of Sound Tools, stereo hard-disk recording/editing, at 20-bit resolution, 128x oversampling, for greater dynamic range and sound quality. Permitted full exploitation of the 96dB potential dynamic range of common 16-bit master distribution formats, through intelligent 20- to 16-bit conversions with dithering. 24-bit data storage and processing format. Two XLR balanced ins/outs with Ultra Analog converters, AES/EBU digital. Included Sound Designer II stereo editing/DSP software; also was compatible with Sound Designer II "plug-ins".@SoundEdit Pro@Macintosh sound editing program, distributed by Macromedia. Capable of editing digital audio files in AIFF and other formats. Very popular among multimedia designers and in the QuickTime environment.@Spectral Enhancer@A type of signal processor, which alters (enhances) the frequency spectrum of the input, especially to augment the listener's subjective impression of high (and sometimes low) frequency content. Spectral Enhancers accomplish this effect either by generating additional harmonics based on the input signal (Aphex), applying equalization which varies as a function of the dynamics of the input signal (Dolby 740), or by applying complex phase shifts which also vary according to the dynamics of the input signal (BBE).@Spectrum Analyzer, Realtime Analyzer, RTA@An electronic device which measures the frequency content of an audio input, usually in increments of 1/3 octave, and displays in real time the changing amplitude levels of the various frequency bands. Often used with a specially calibrated omnidirectional microphone, in particular to measure the frequency response of speakers or rooms. Spectrum Analyzers also often incorporate "Pink Noise" generators; they can be used in conjunction with this microphone and a graphic equalizer to create an equalization curve for an audio monitoring system, which compensates for the irregular frequency response curve in a room or hall. Since the display operates in real time, this device is also known as a Real-Time Spectrum Analyzer.@Speed of Sound@At sea level, 70ûF (21ûC), sound waves are propagated through air at approximately 1129 feet per second (344 meters/second). Therefore, sound waves traveling from a source that is 112.9 feet (34.4 meters) from the listener, take about 100 milliseconds to arrive through the air. Sound transmission through a liquid is faster (and more efficient) than through air; transmission through a solid (e.g. bass frequencies transmitted through the floor of a nightclub) is even faster. When designing or installing sound reinforcement and monitoring systems, these relationships between distance and the speed of sound must be taken into account if Phase Cancellation and Precedence (Haas) Effects are to be properly taken into account.@Spindle Speed@The speed at which the platters of a hard drive rotate; the spindle is the hub, or center portion of the disk drive, applying the force by which spins the disk. In general, faster rotation speeds (higher revolutions per minute, or r.p.m.), mean higher data transfer rates, as the recorded information is passing by the read/write heads at a faster speed. (Higher speeds of rotation also slightly reduce rotational "latency" intervals, see definition for Access Time.) Spindle speeds of 3600 to 7200 r.p.m. are common for hard disks, while a diskette rotates at 300 r.p.m. Audio users take note: some disk drives with higher spindle speeds emit a high-pitched whine, and can be an even greater problem for audio recording than standard disks (which are noisy enough!). It is wise to check the noise level of a disk drive (rated in decibels), before purchasing. See also Transfer Rate, Access Time, Hard Disk.@SPL@Sound Pressure Level. The acoustical energy (air displacement) of a sound source, as measured from a given point. Measured in decibels (dB), above a reference pressure level of 0.0002 microbars (the minimum threshold of human hearing).@Splice@Joining two pieces of film, cable or tape together in a seamless fashion. In particular, the technique of joining together two segments of magnetic tape, using a special non-bleeding adhesive tape called splicing tape. Commonly used for audio editing before the advent of DAWs, this technique is now mostly used for assembling analog master tapes, inserting paper leader, etc.@Split (MIDI Keyboard)@On MIDI instruments, a means of creating independent zones on a single keyboard, which can send out (or respond to) data on different MIDI channels, and/or respond with different timbres, according to the position of notes within the ranges of keys (note numbers) which are defined by the Split. See also Layer.@Split Stereo@Digidesign term. Two mono files which represent the left and right channels of stereo material (instead of a single interleaved stereo file). Stereo mixes from Pro Tools can be "Bounced" to disk in this split format, which creates two separate mono files. This is most useful for creating stereo submixes during the Pro Tools editing process. Sound Designer II can also edit and save stereo audio consisting of two separate files on disk, with .L and .R after their filenames. The Split Stereo format facilitates subsequent transfer of stereo audio material into Pro Tools or Session 8 (avoids delays and additional disk space utilization, caused when the Import Audio command must split the interleaved stereo source file into two new mono files).@Spot@A radio or television commercial advertisement, a commercial.@Spot Mode@Digidesign Pro Tools term. One of the four editing modes, activated by clicking the Spot button in the Edit window of the Pro Tools program. Useful in audio-for-video editing for "spotting" of audio or MIDI Regions to specific SMPTE frame locations. In Spot mode, when the "Grabber" tool is used to click on a Region in a track, it will be immediately moved to the current incoming SMPTE timecode location. A dialog appears allowing you to either accept this location, or manually enter a different numerical SMPTE location. Also, in Spot mode, when a Region is dragged from the Regions List into a track, the SMPTE time location dialog appears upon releasing the mouse button. Regions are always spotted by their start times, unless a Sync Point has been identified within the Region, in which case the Sync Point itself is aligned to the specified timecode location. See also Shuffle Mode, Slip Mode, Grid Mode, Spotting, SMPTE TimeCode.@Spotting@The process of identifying, and documenting, time references for the locations on a film or video where musical cues and sound effects should occur (often compiled in a document called a "Cue List". Spotting also can refer the actual assembly process, where audio and music cues are placed into the soundtrack according to these numerically designated timecode locations. Digital audio editing programs often use the term Spotting to designate an editing mode where the placement of audio segments is handled numerically, according to time references such as SMPTE TimeCode. See also Cue.@Square Wave@A type of basic audio waveform, which consists of a fundamental tone and odd harmonics only (i.e., an infinite series of sine wave overtones, at frequency relations of 1, 3, 5, 7, 9, etc.). The amplitude of the each harmonic diminishes in proportion to its integer multiple of the fundamental frequency. For example, the amplitude of the harmonic at 3 times the fundamental (lowest) frequency is 1/3 that of the fundamental, the 5th harmonic's amplitude is 1/5, etc. When viewed on an oscilloscope, an ideal square waveform passes directly from a steady level of positive displacement to a corresponding negative displacement, staying at each phase of its excursion during equal intervals of time. No audio system can reproduce a pure square waveform: for example, any loudspeaker takes some minimum amount of time to travel from the positive excursion to the negative. Therefore, there will be some slope in the resultant waveform, where the transitions from positive to negative occur.@SR@Sound Reinforcement. The amplification of an acoustic or electronic source, so that it can be heard clearly from a longer distance, and/or by a greater number of people. Also: the art and science of doing this correctly.@SR Convert@Sample Rate Convert. A menu option in Digidesign's Sound Designer II program. Used for generating a new, separate audio file from an existing one, at a higher or lower Sample Rate; a process also sometimes known as Transcoding, or Resampling. See Sample Rate.@SRAM@Static Random Access Memory, a high-speed type of computer RAM, often found in "Level 2" cache memories and cards. See RAM, DRAM, Cache.@SRS@An emerging standard for simulation of 3-dimensional placement of sound sources, from a stereo source. Related to Spatializer 3-D products from Spatializer Audio Labs, who also offer a sound-imaging enhancement plug-in software module for Pro Tools/TDM.@SSA, Serial Storage Architecture@Computing term. A high-speed bus for the serial connection of disk drives and other data storage peripherals to computers. Capable of data throughput at speeds of 70 to 80 megabytes per second, it was adapted from an earlier serial data connection standard used on IBM mainframe computers. Since its introduction 1995, SSA has been promoted by several computer manufacturers, including IBM, as a faster alternative to SCSI. See also SCSI, 1394.@Standard MIDI File, SMF@A standard interchange format for MIDI files, useful for transferring recorded files from one programÕs native format to another. Includes all MIDI events, channels, track names, etc. Some programs and devices (such as hardware-based sequencers) are better at importing/exporting these files than others. There are two types of SMF files: Type 0 files combine all channels into a single, multi-channel track, while type 1 files maintain separate tracks for each MIDI channel, and also retain individual track names. Also abbreviated SMF.@
