Audio Terminology And Definitions Dictionary

 

S-Video  S-Video is a type of interface between analog video sources and downstream components, either A/V receivers or displays. With an S-Video connection, black-and-white (luminance) and color (chrominance) portions of the signal are separated and transmitted through separate conductors in a cable that is terminated with a multi-pin DIN-type connector. The result is less color bleeding and more-defined edges than with a standard analog composite video connection.

 

SACD (Super Audio Compact Disc)  SACD (also called SA-CD) is a high-resolution audio disc format developed by Sony and Philips and is based on a proprietary Direct Stream Digital (DSD) format. SACD is capable of more accurate sound reproduction than the Pulse Code Modulation (PCM) format currently used for CDs.

 

Sampling Rate  In order to convert an analog signal to a digital file, a series of digital "snapshots" or samples of the signal are made (See also: PCM). Collectively, these samples represent the digital version of the analog sound. The higher the sampling rate, the more accurate the sound reproduction. Sampling rate is usually given in hertz (Hz). CDs use a sampling rate of 44.1 kHz, which represents 44,100 samples per second. Blu-ray discs can have sampling rates of up to 96 kHz, or 96,000 samples per second. SACDs (Super Audio CDs) have a sampling rate of 352 kHz, or 352,000 samples per second.

 

SCART    Short for Syndicat des Constructeurs d'Appareils Radiorecepteurset Televiseurs, this single-cable audio/video interface format is far more common in Europe than in North America. SCART connectors have 21 pins, with each pin (or groups of pins) assigned to pass either an analog video or analog audio signal. SCART connections can be configured to pass Composite, S-Video or Interlaced (Y, Cb, Cr) Component and RGB analog video signals and conventional stereo audio. SCART connectors cannot pass progressive scan or digital video or digital audio signals.

 

Screen Door Effect  The Screen Door Effect is an LCD artifact that is primarily associated with older LCD video projectors. LCD projector images are composed of individual pixels that are separated by black borders. If the projected image is large or the pixel count is low, these borders become visible and produce the effect of seeing an image through a "screen door." Recent developments have reduced the visibility of a pixel's black border and have virtually eliminated this artifact in recent projectors.

 

Screening  A form of protection of conducting cable from radio interference.

 

SDII (Sound Designer II)   An audio format for Macintosh operating systems which is often employed by pro-quality sound editing software applications. SDII files, like AIFF and WAV files, are capable of storing uncompressed CD-quality audio.

 

SDMI (Secure Digital Music Initiative)   This standardizes digital music file specifications. SDMI's primary purpose was to create a uniform copyright protection protocol that would work with a variety of digital players, software programs, and download sites. SDMI-compliant devices and files have special coding in order to recognize and comply with the requirements imposed on copyright-protected materials.

 

SECAM   Known variously as Sequential Colour A'Memoire (French), Sequential Color With Memory (English), or "Something Contrary to American Methods," SECAM is a video system originally developed in France. While superior to NTSC, SECAM is not necessarily superior to PAL. SECAM is a 625-line, 50 fields at 25 frames per second interlaced system with a different method of handling color components of the video signal. Countries using SECAM include France, Russia, Eastern Europe, and some parts of the Middle East.

 

Selectable Output Control  This term describes a cable or satellite provider's ability to disable 720p/1080i/1080p output from a set-top box via component video outputs. This ability may be invoked at the discretion of the movie studios or cable/satellite provider.

 

Selectivity  The ability of a radio tuner to select or separate stations transmitting on nearby frequencies. By reducing the IF (intermediate frequency) bandwidth to sharpen selectivity, there may be a tradeoff in the form of increased distortion. Some sophisticated tuners provide switchable selectivity so that when two adjacent stations are required to be separated, users may do so by choosing narrow IF selectivity, at other times reverting to wide selectivity to benefit from the natural reduction in distortion.

 

Separation   Stereo separation is a measure of the success in isolating left and right channel stereo signals. The higher the dB specification the better.

 

Sensitivity     Sensitivity has many meanings in audio/video. It can be the measure of how well a tuner circuit will pick up a weak signal. This is usually measured in microVolts or dBf (decibels per femtoWatt). Lower numbers are usually better. Sensitivity can also mean the measure of how loud a speaker will play with a standard input voltage applied at the terminals. In this case, sensitivity is usually expressed as "XX dB SPL for 1 watt input (or 2.83 volts, the equivalent at 8 ohms) measured at 1 meter." Sensitivity is not a measure of a speaker's sound quality; it is only a reflection of how loud it will play with a given input. (See also: efficiency.)

 

Series/Parallel  See Parallel/Series.

 

SHN (Shorten)  SHN is a lossless form of compression for digital audio. A Shorten file is only about half the size of its original WAV or AIFF source. Unlike lossy audio codecs (such as MP3, WMA, etc.), SHN is capable of reproducing the original audio signal in its entirety, without removing frequencies. Because of this, SHN offers significantly better sound quality than MP3. However, since SHN files are significantly larger than MP3 files, SHN isn't nearly as convenient when storage space and download times are a concern.

 

Signal-to-Noise Ratio (SNR)    SNR is the difference in level, measured in dB, between a desired signal and residual noise inherent a circuit or an entire component. All else being equal, higher signal-to-noise measurements usually indicate better performance potential.

 

Sine Wave   Continuous waveform of a particular frequency (cycles per second).

 

Single-Beam Laser Transport     An optical laser assembly that uses a single beam to read the "bumps and pits" off a compact disc (CD). (See also: three-beam laser transport.)

 

Slit Foil Capacitors  These specially designed power supply capacitors are manufactured for high-end audio in Great Britain. Their unique properties include a low dielectric loss with extremely fast time constants (charge/discharge time) in relation to their storage capacity. In operation, these capacitors emulate the design achievements of many esoteric products that use a very large number of smaller capacitors to achieve much the same effect, albeit at substantially higher cost.

 

Slope  The rate at which a filter circuit (high-pass, low-pass, crossover, etc.) attenuates out-of-band frequencies. Slope is usually measured in decibels per octave (abbreviated dB/octave). Typical slopes are 6 dB/octave (first order), 12 dB/octave (second order),18 dB/octave (third order), etc.

 

Smoothing Capacitor   An important component in a power supply, the smoothing capacitor(s) eliminate(s) unwanted ripple, the remains of the positive half cycle  of AC mains following rectification.

 

SMPTE    Society of Motion Picture and Television Engineers.

 

Sound Pressure Level (dB/SPL)     A loudness measurement in decibels. Normal room conversation is around 60 dB SPL; a loud rock concert is about 100 dB SPL; a jet airliner taking off is in excess of 130 dB SPL.

 

Speaker (Speaker System or Loudspeaker)    A system with three sub-components: drivers, an enclosure, and (usually) a crossover network. Speakers are transducers that convert one form of energy (in this case, an electrical signal) into another form (acoustical energy). Speaker systems can be freestanding (totally enclosed in an enclosure or cabinet), they can be placed on a bookshelf or on the floor, or they can be installed into a wall or ceiling.

 

Square Wave  A waveform designed to simulate a transient impulse such as that of percussion instrument. Derived from a sine wave, a square wave can be shown by technical analysis to contain a multitude of harmonics. It is a very difficult test of hi-fi equipment and therefore particularly useful.

 

Star Earth Grounding   A technique used by designers to ensure that there is no degradation of sound or acquired "ground loops" by poor "earthing" arrangements. The star earth grounding, or "Y" connection, routes all ground wires to a single point in the design with the resulting wire arrangement looking somewhat like a star pattern.

 

Stereo   Literally means solid. Usually taken to refer to two-channel audio

 

Streaming (Media Streaming)  This term is usually used in connection with audio, video, or audio/video data and describes one of several methods of transferring data so that it can be processed as a steady, continuous stream. Streaming technologies are increasingly important in light of the growing prevalence of high-speed Internet connections. The "client side," or the receiving end, of the streaming data must be able to collect it and send it as a steady stream to the application that is processing the data. After that processing, the data is converted to sound and/or visual images. This process usually requires a buffer that temporarily stores the data until downstream components need it. RealAudio is an example of a program developed for audio streaming.

 

Stylus   The needle part of a cartridge, the tip of which makes contact with a vinyl record. Elliptical, and super-elliptical (e.g. fine line and Shibata) tipped styli are preferable to conical styli (found only on the cheapest, most unsophisticated cartridges.

 

Subwoofer    A separate speaker designed specifically for the accurate reproduction of low-frequency information.

 

Surround Sound System  A generic term that describes a system designed to reproduce sound through several (usually four or more) speakers in order to produce a sense of envelopment in which the listener/viewer is immersed in sound coming from many directions at once. Almost all home theater systems worthy of the name provide this capability.

 

Surround Speaker     Any speaker used to reproduce the side and/or rear channel information in a home theater system.

 

SXRD (Silicon X-tal Crystal Reflective Display)   Developed by Sony, it is a variation of LCOS technology. (See also: LCOS.)

 

Symmetrical Circuit Layout  A method of circuit configuration that lays out both the left and right halves of the design in a "mirror image" of each other. The result is matched electrical performance from both channels for superb stereo resolution.