Primer
Crestron
Surround Sound
O
L
LFE
Octave
Low Frequency Effects
1. In music, an octave is a doubling or
halving of frequency with the bottom octave
usually given as 20 to 40 Hz.
Lossless
A term describing a data compression
algorithm that retains all the information in
the data, allowing it to be recovered perfectly
by decompression.
2. In parametric equalizers, it is the range of
frequencies above and below a selected
center frequency that are affected by the
change in amplitude.
Lossy
A term describing a data compression
algorithm that reduces the amount of
information in the data, rather than just the
number of bits used to represent that
information. The lost information is usually
removed because it is subjectively less
important to the quality of the data or
because it can be recovered by interpolation
from the remaining data.
P
Parametric Equalizer
Type of equalizer that allows adjustment of
frequency response with complete choice of
center frequency, amplitude, and bandwidth.
PCM
Pulse Code Modulation. A method of
transferring analog information into digital
signals by representing analog waveforms
with streams of digital bits.
LPCM (linear pulse code modulation)
A means to digitally represent signals in
which the amplitude of a signal is coded as a
binary number.
Perceptual Coding
A coding method that exploits limitations in
human hearing acuity to decrease the bit rate
of the audio bitstream.
M
Masking
Phantom Image
Under ordinary conditions, the process by
which the threshold of hearing of one sound
is raised by the presence of another. In both
digital video and digital audio, a technique
that allows a system to delete superfluous
(inaudible or invisible) artifacts from a data
stream by means of data reduction or data
compression, enabling the system to transmit
or store wide-bandwidth information within a
much smaller bandwidth. Four uses of
masking involve Dolby AC-3 Digital
Surround Sound, MPEG video, DCC
cassettes, and the MiniDisc.
A virtual sound source detected by a listener
but not actually produced by a speaker at that
location.
Pink Noise
Random noise (hiss) that has equal energy in
each octave, and is used for setting and
balancing a surround system. Pink noise is
used as a test tone featuring equal amount of
energy per octave of bandwidth. Compare
this to white noise, which features an equal
amount of energy per Hz (cycle per second)
of bandwidth. Pink noise and white noise are
common test signals with pink noise used
frequently to adjust equalizers for a flat
frequency response.
Matrixing
A technique in which additional signals can
be conveyed by altering the phase
relationships of the signals.
Pinna
The outer part of the ear
MPEG (Moving Pictures Expert Group)
A committee developing audio and video
standards.
S
SACD (Super Audio Compact Disc)
A standard for high-density storage of two-
channel CD and two-channel and
multichannel SACD audio recordings.
N
Nyquist Sampling Theorem
Mathematical theory that a signal can be
completely represented by a sampling signal
with a frequency that is at least twice the
highest input signal frequency.
SDDS (Sony Dynamic Digital Sound)
A perceptual coding method used in some
theatrical motion picture releases.
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Surround Sound
Primer – DOC. 6122
