Lexicon DC-1 - ADDENDUM Owner's Manual Addendum page 9

Introduction
Thank you for your purchase of this upgrade for your DC-1. This Owner's
Manual Addendum is designed to provide supplementary information for
systems with Dolby Digital® AC-3 Version 2.00 or DTS® software installed.
About Dolby Digital AC-3 Encoding
Because multichannel recordings are made up of so much information, new
ways of storing and transmitting data have been created. Dolby Laborato-
ries developed AC-3, a digital audio coding technique on which the Dolby
Digital surround format is based.
On a typical compact disc, 16-bit samples are taken 44,100 times per second
for each channel. This allows as much as 74 minutes of 2-channel audio on
a single CD. However, if a digital recording consists of six channels, up to
two hours in length, storage or transmission becomes impractical due to the
immense amount of data. Therefore, new forms of digital audio coding
(sometimes referred to as "perceptual coding") have been developed to
allow the use of lower data rates with a minimum of perceived degradation
of sound quality.
Designed specifically to handle multichannel audio, AC-3 takes advantage
of a psychoacoustic phenomenon known as auditory masking. It divides
the audio spectrum of each channel into narrow frequency bands of
different sizes optimized with respect to the frequency selectivity of human
hearing. This makes it possible to sharply filter coding noise so that it is
forced to stay very close in frequency to the frequency components of the
audio signal being coded. By reducing or eliminating coding noise wher-
ever there are no audio signals to mask it, the sound qulity of the original
signal can be subjectively preserved. The result is multichannel sound that
is subjectively equal to 2-channel digital recordings, which can be stored
and transmitted efficiently.
About DTS Encoding
DTS Digital Surround is a format that utilizes an encode/decode system to
deliver up to six discrete channels of high quality digital audio. Like the
Dolby Digital format, DTS Digital Surround is often referred to as a 5.1
channel format because it is capable of 5 full range channels in addition to
a limited range Low Frequency Effect channel (LFE).
Originally introduced to the public in 1993 with the theatrical release of
Jurassic Park, DTS Digital Surround has become one of the most widely
used digital playback systems in movie theaters. DTS Digital Surround
competes with alternative discrete digital formats such as Dolby Digital
(AC-3) and Sony Discrete Digital Surround (SDDS).
For the consumer, DTS Digital Surround software is currently available on
a limited number of laser discs and music discs. Playback of DTS Surround
media REQUIRES the use of a DTS Surround decoder. Playback without an
appropriate decoder may cause serious damage to your system.