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Surround Sound
(How many speakers do we really need?)
Why surround?
• Ever since the 1950’s, great steps have
been taken in order to create the ultimate
home-entertainment experience.
• Walt Disney attempted to create a
surrounding sound experience with the
viewing of Fantasia. The surround sound
process was called “Fantasound”
• Single source of sound
– Usually, a TV speaker or a radio transmission
– This source is referred to as a “channel”
Dual source of sound
– Involves the use of two speakers, or
“channels,” paired as a Left and
– Dubbed as “Hi-Fidelity”
– In Dolby, this is considered AC-1,
because one track carries both
Quadraphonic Stereo
Dolby Surround
• Two (2) audio tracks are used: Left and Right (track
1), and Mono Surround (track 2)
• These two tracks are carried on stereo program
sources such as videotapes and TV broadcasts into
the home
• This was dubbed as “AC-2”, because two tracks
were used to carry three channels of sound.
Dolby Surround
Dolby Pro-Logic Surround
• Like Dolby Surround, Dolby Pro-Logic Surround
used the original two tracks of audio – Left and
Right (track 1) and Mono Surround (track 2) – while
adding a third track for the Center channel (track 3)
• This new track was used with a filter system that
generated all “direct front” sound (such as actor’s
voices) to appear as though it was centered (hence,
the “center channel”
Dolby Pro-Logic Surround
Dolby 5.1 Digital Surround
• The speaker arrangement uses six channels (only
available on DVD and Blue-Ray): Left, Right, Center,
Surround Left, Surround Right, and the LowFrequency Channel (subwoofer).
• Dolby 5.1 Surround is dubbed so because the .1
LFE (subwoofer) channel is not a constant sound
generator. It is actually triggered, on occasion, to
• This Dolby technology truly uses separate stereo
surround signals, versus the original mono
channels available in Dolby Surround and Dolby ProLogic. (AC-3)
Dolby 5.1 Digital Surround
Dolby EX (THX) Surround
• Dolby Digital EX takes the Dolby Digital 5.1-channel
setup one step further with an additional center
surround channel (reproduced through one or two
speakers) for extra dimensional detail and an
enveloping surround sound effect.
• Feature films originally released in Dolby Digital
Surround EX (the cinema version) carry the
encoded extra surround channel in their
subsequent DVD releases, as well as onto 5.1channel digital satellite and TV broadcasts.
• Also known commercially as THX
Dolby EX (7.1) Surround
Dolby Digital Plus
• Dolby® Digital Plus is the next-generation audio
technology for all high-definition programming and
• Can deliver 7.1 channels and beyond* of enhancedquality audio
• Allows multiple languages
• Compatible with the millions of home
entertainment systems equipped with Dolby Digital
Ray Dolby
• Received a B.S. in electrical
engineering from Stanford
University in 1957 and a Ph.D. in
physics from Cambridge
University in 1961
• Ray Dolby has been inducted
into the National Inventors Hall
of Fame in recognition of his
invention of Dolby noise
Ray Dolby
• Founded Dolby Laboratories in
1965 to further develop his ideas
about noise reduction
Patrons of Dolby Surround
Pioneer Electronics
Sony Corporation
Kenwood Electronics
Creative Labs
Consumers of Dolby Surround
• Audiophiles and Media
enthusiasts were the
original target audience
for the Dolby Processing
• After the HomeEntertainment Industry
really finally took off,
every consumer in the
general public became
the target market of
Dolby Laboratories.
Rarely, can there be found any
piece of home entertainment
equipment without the Dolby
logo emblazoned on it.
Producers of Dolby Surround
Manufacturers of Home
Entertainment equipment are
not the only prospects of Dolby
Laboratories. Movie and
Television production
companies are Dolby’s
greatest advocates, investing
millions of dollars per
production in the audio
processing alone.
Every audio cassette, CD-Rom,
VHS cassette, DVD-Rom, and
Blue-Ray Disk are encoded
using some form of Dolby
Meeting the Needs and Wants
Recreating a true-to-life environment, even in a surrealistic one
that Hollywood can conjure up, is the ambition of every
entertainer, director, and producer. When not only the sights
but the sounds help to establish the make-believe world as a
viable option for escapism, then the needs and wants of
consumers have been met. And, if the needs and wants of the
consumers have been met, then the needs and wants of those
in the production of audio and video have been met.
Today, the newest benefactors of this technology are those
who dwell in the video game arena, with just about every game
in the market produced in multi-channel surround mode.
Gamers everywhere can thank Super Nintendo and the 1994
game “Jurassic Park” – the first video game ever to be
produced in Dolby Surround Sound.
The Trade-offs
With the more dynamic the audio system, the more complex it
becomes to set it up, and the more expensive it is to get things
going. Multi-Channel surround systems, whether Dolby, DTS
(Digital Theater System) and THX, the more speakers there
are, the more the system costs. And, because the idea of going
“digital” is such a big deal, the sound systems and their
peripherals can cost an arm and a leg. Thankfully, consumer
grade equipment is quite manageable.
Home Theater Systems are not unlike Computer systems, in
that they seem like a never-ending arms race of the biggest
and baddest of technologies. Upgrading and maintenance are
constantly on the minds of uber-audiophiles and entertainment
enthusiasts who just have to have the best.
•Dolby Technologies: Dolby.com
•About.com: The History And Basics Of Surround Sound Dolby Surround
•Broadcasterbuyer.com: Ray Dolby Inducted Into The
National Inventors Hall Of Fame
•Atlantic Technology Timeline