Audio Terminology And Definitions Dictionary
A Common abbreviation for ampere (see
AB Switch A coaxial cable switch capable of
switching one cable to one of two branch cables, A or B
Audio Coding) A computer-audio file format developed as an improvement on the
MP3 format. AAC uses more advanced compression and, according to some, delivers
better sound at lower bitrates (98 Kbps) when compared to MP3s encoded at higher
bitrates (128 Kbps), despite a smaller file size. The current version of AAC was
developed as part of the MPEG4 standard. Versions are now used by Apple in their
popular iTunes Store, as well as Sony in their PlayStation3 game consoles. Files
may appear with the ".m4a" or ".mp4" filename extension.
abbreviation for alternating current.
called Dolby Digital. A method developed by Dolby Laboratories for "compressing" (or reducing) the amount of bits needed to convey
multi-channel, full-bandwidth digital sound for a wide variety of formats,
including DVDs, laserdiscs, and television and satellite broadcasts.AC-3's
potential benefits include fully discrete sound for five full-bandwidth channels
and one low-frequency (subwoofer) channel, as compared to earlier "matrix"
formats with mono surround and a derived subwoofer channel. The "AC" stands
for "audio codec" while the "-3" identifies this method as the third one
developed by Dolby for this purpose. (See also: Dolby
Digital and Dolby Stereo Digital.)
filter used in some advanced home theater controllers to compensate for the
overly bright soundtrack of many earlier films. This filter operates only in the
mono mode and begins attenuating high frequencies just below 2 kHz. It reaches
maximum effect (-16 dB) at 10 kHz. Note that the "Academy" filter is not
the same as "Re-equalization." Re-equalization is a technique
unique to THX processing in which high-frequency content to all front channels (LCR) is reduced less radically.
Acoustic Suspension A
completely sealed enclosure that typically houses at least a woofer. Air trapped
inside the enclosure acts as a spring to restore the woofer's diaphragm to its
equilibrium position after movement. Acoustic suspension enclosures generally
provide more linear bass response than horn or bass reflex enclosures. Acoustic
suspension speakers are usually characterized by accurate bass response.
A/D (ADC) Analog/Digital; an integrated
circuit device that converts analog signals to digital signals.
(Audio Interchange File Format) An audio format for Macintosh operating
systems that is commonly used for storing uncompressed, CD-quality sound
(similar to WAV files for Windows-based computers). AIFF is considered a
lossless container format.
Lossless Audio Codec) ALAC is a lossless audio compression format
developed by Apple that provides full CD-quality audio in about half the space
of the original file.
Alternating Current Electricity in the
form of sine wave (i.e. with positive and negative halves of a continuous
waveform). Mains electricity is in the form of alternating current (AC).
surrounding "atmosphere" that frames more intense sounds. In audio
reproduction, ambience means the subtle, very low-level sonic cues that describe
the acoustic environment in which a recording was made. In video, these very
faint sounds (wind or traffic noise) add to the reality of a scene. Often
recorded separately from the dialog or main effects tracks, they are usually
added later in the "post-production" phase of preparing a film for release.
(Sometimes called atmospherics.)
Ambisonics A recording/replay system
developed in the Seventies to improve three dimensional stereo definition by
means of a special microphone recording technique, encode/decode electronics and
a multiple surround sound loudspeaker playback system.
Amplifier An electronic device or
product designed to turn a small signal into a larger one. An integrated
amplifier accepts input signals, has source selection and volume controls and
provides an output sufficiently high to drive loudspeakers. A power amplifier,
simply the loudspeaker driving half of an integrated amplifier. A pre-amplifier,
the first half of an integrated amplifier, provides inputs for the various
source signals, switching between sources and a number of controls (eg volume,
balance, tone and other signal processing). Most hi-fi amplifiers contain two
channels (left and right stereo). A monoblock power amplifier is a single
channel amplifier. Two are required to drive a stereo pair of loudspeakers.
Multi-channel amplifiers are required for surround sound systems. For instance a
fully fledged Home THX system requires five channels of amplification (left,
center and right front, plus two rear channels). An extra power amplifier is
sometimes required if a subwoofer (very deep bass loudspeaker) is used to
supplement the low frequency output of the system.
Amplitude Modulation A form of radio broadcast, (abbr:
AM); literally means that the carrier frequency is modulated, or varies,
in size (amplitude) according to the content of the transmitted signal.
Analog Television This
refers to a video display device that receives and displays broadcast television
signals. The video portion of an analog TV signal is transmitted in AM, while
the audio is transmitted in FM. Analog television signals were (and still are,
in some cases, with educational or other low-powered transmissions) broadcast in
interlaced format, with the image's odd lines transmitted first, then the even
lines. Full-power analog television broadcasting in the U.S. ended in 2009.
Anechoic Non-reverberant. An anechoic chamber is an acoustically dead room designed primarily for
the purpose of accurate loudspeaker measurement.
Aspect Ratio Aspect
ratio defines the horizontal width of a video image or screen in relation to it
its vertical height. For example, traditional analog television had an aspect
ratio of 4x3 (4 units in width, 3 units of height). HDTVs have a "widescreen" ratio of 16x9. Alternately, 4x3 is often referred to as 1.33:1
(1.33 units of horizontal width against 1 unit of vertical height), and 16x9 is
expressed as 1.78:1 (1.78:1 units of horizontal width against 1 unit of vertical
Transform Acoustic Coding) Developed by Sony engineers in the early 1990s for
the MiniDisc format, ATRAC is a lossy audio codec that is said to offer near-CD
quality sound with relatively small file size. (ATRAC3 and ATRAC3+ are advanced
versions of the codec, and they boast even smaller file sizes and reduced
Advanced Television Systems Committee, which wrote the specs for high-definition
To reduce or lower the strength or level of a signal. Attenuation can take place
at many points in a signal path, the most common of which is the volume control.
audio format commonly used for posting sound clips on the Internet. AU files can
be played back on Windows, Macintosh, and other operating systems..
Audio A term used to describe sounds within the range of
human hearing. Also used to describe devices which are designed to operate within this range
Audio Return Channel
(ARC) A feature of HDMI (version 4.0 and later) that allows a user to transfer
audio from the TV back to a home theater receiver in order to listen to TV audio
through a home theater speaker array without having to connect a second cable
between the TV and home theater system.
Audyssey DSX Audyssey's
Dynamic Surround Expansion, which adds front vertical-height speakers, similar
to Dolby Pro Logic IIz, and left and right wide speakers positioned between the
front left and right and surround left and right speakers.
Auxiliary Bass Radiator A loudspeaker drive unit fitted to a box loudspeaker, coupled acoustically but not electrically
to the input signal. Functions somewhat like a port or tuned tube in the loudspeaker cabinet supplementing
bass output and aiding loudspeaker sensitivity.
A/V Receiver An
AV receiver combines the functions of three components:
· An AM/FM radio tuner and, in some cases, HD
(high-definition radio) or SiriusXM satellite radio capability.
· A preamplifier/processor that switches and controls audio
and video source selection and routes audio and video signals for further
processing as required.
· A built-in multi-channel amplifier (5.1, 6.1, or 7.1
channels) that sends surround sound audio signals and power to the speaker
jointly by Panasonic and Sony, AVCHD (Advanced Video Codec High Definition) is a
high-definition digital video format for recording 1080i and 720p signals onto
MiniDVD discs, MiniDV tape, hard drives, and digital camera memory cards. AVCHD
uses a very efficient compression format known as MPEG4 (H264).
file format for storing and playing back movie clips with sound on Windows
computers. An AVI file is organized into alternating ("interleaved")
chunks of audio and video data. AVI is a container format, meaning that it
specifies how the data will be organized, but it is not itself a form of audio
or video compression.
AWG American Wire Gauge; a wire diameter specification,
the lower the AWG number the larger the wire diameter.