SEMINARON

SURROUND SOUND SYSTEM

Guided By : Prof. Amol C WaniPresented By: Chetan V Gakhare

Content: What is Surround sound? Early surround sound Generalized Surround sound arrangement Creating surround sound 5.1 Channel surround sound Other surround sound specifications Design of home theatre using HDMI Surround Sound Formats Applications Conclusion References

What Is Surround Sound? Surround sound is a technique for enriching the sound reproduction quality of an audio source with additional audio channels from speakers that surround the listener, providing sound from a 360° radius in the horizontal plane (2D) as opposed to "screen channels“ originating only from the listener's forward arc.

Early Surround Sound The first use of surround sound

was in 1940, for the Disney studio's animated film Fantasia. The sound was diffused throughout the cinema, initially by an engineer using some 54 loudspeakers.

In 1978, Superman movie “Apocalypse Now “ made the first formal release of surround sound in cinemas with three channels in the front and two in the rear by Dolby lab.

Center speaker carries most of the dialogue and part of the soundtrack. 

Left and right front speakers that carry most of the soundtrack and may carry parts of the dialogue

Pair of surround sound speakers that is placed to the side (and slightly above) of the audience to provide the surround sound and ambient effects. 

Finally, a subwoofer can be used to reproduce the low and very low frequency effects (LFE) that come with certain movies

Generalized Surround Sound Arrangement

Creating surround sound

The first and simplest method is using a surround sound recording microphone technique

A second approach is processing the audio with psychoacoustic sound localization methods

A third approach, based on Huygens' principle, attempts reconstructing the recorded sound field wave fronts within the listening space; an "audio hologram" form.

Monophonic Sound

Monophonic sound is a single-channel, unidirectional type of sound reproduction.

To the ear, all the elements of the sound, voice, instruments, effects, etc... appear to originate from the same point in space.

Stereophonic Sound

The main aspect of Stereophonic sound is the division of sounds across two channels.

The recorded sounds are mixed in such a way that some elements are channeled to the left part of the soundstage; others to the right.

Extracts Five audio channels :- Two channels for speakers

at the front—left (L) and right (R).

One channel for speaker at the center—center (C).

Two channels for surround speakers at the rear—surround left (LS) and surround right (RS).

One low-frequency effects channel (LFE).

5.1 Channel Surround Sound ( ITU-R BS. 775-1 Standard)

3.0 Channel Surround Extracts 3 audio channels :-

Two channels for speakers at the front—left (L) and right (R).

One channel for surround speaker or speakers at the rear—surround (S).

Other surround sound specifications

4.0 Channel Surround (analog matrixed/discrete: Quadraphonic)

Extracts four audio channels :-

Two channels for speakers at the front—left (L) and right (R).

Two channels for surround speakers at the rear—surround left (LS) and surround right (RS).

4.0 Channel Surround (analog matrixed: Dolby Pro Logic)

Extracts four audio channels :- Two channels for speakers

at the front—left (L) and right (R).

One channel for speaker at the center—center (C).

One channel for both surround speakers at the rear—mono surround channel (S).

6.1 Channel Surround (analog matrixed: Dolby Pro Logic IIx)

Extracts six audio channels and one low-frequency channel :- Two channels for speakers at

the front—left (L) and right (R).

One channel for speaker at the center—center (C).

Two channels for surround speakers at the sides—side left (LS) and side right (RS).

One channel for surround speakers at the rear—back surround channel (BS).

7.1 Channel Surround (digital discrete: Dolby Digital Plus, DTS-HD, Dolby TrueHD)

Delivers seven audio channels and one LFE channel :- Two channels for speakers at the

front—left (L) and right (R). One channel for speaker at the

center—center (C). Two channels for surround

speakers at the sides—left surround (LS) and right surround (RS).

Two channels for surround speakers at the rear—left back (LB) and right back (RB).

Zero-based order within multi-channelmp3/wav/flac datastream.

Order withinDTS/AAC. Channel name

Color-coding on commercial receiver and

cabling

0 1 Front left White1 2 Front right Red2 0 Center Green3 5 Low frequency Purple4 3 Surround left Blue5 4 Surround right Grey

6 6 Surround back left Brown

7 7 Surround back right Khaki

Channel Identification

Design Of Home Theatre System Using HDMI Transreceiver

This system “Home Theatre In Box” generally include a multichannel audio amplifier and a surround-sound speaker system for playback of audio.

In addition, these system usually include a DVD or Blu-ray™ video player. HTiBs ease installation and power matching between the video player, amplifier, and speakers. HTiBs principally process audio; the video is passed through to the TV over the HDMI interface.

A new feature in the HDMI specification provides for an audio return channel (ARC)—to allow the HTiB to process audio from the downstream device.

Another use of an HDMI transceiver within an HTiB is to extract the HDMI audio for processing with a digital signal processing (DSP) chip. The audio can then be reinserted into the HDMI stream to the TV.

Since many TVs cannot handle multichannel audio formats, the DSP chip can downsample the audio to stereo and then reinsert the audio into the HDMI link to the TV.

Surround Sound Formats

Dolby Pro Logic

Dolby Digital

DTS

THX Surround EX

SDDS

Dolby Pro Logic

It is the simplest, cheapest format.

It has 4 channels that are compressed into two analog channels, so you can record it on your stereo VCR and it can also broadcasted even over analog radio or cable TV.

Dolby Pro Logic

Dolby Digital

It is a 6-channel format, referred to as 5.1-channel

Advantages over Dolby Pro Logic include the fact that all channels are digital, discrete and 5 of them are full-bandwidth.

Additionally, the surround speakers use separate left and right channels (stereo).

DTS

DTS is also a 6-channel format (5.1-channel).

The main difference from Dolby Digital is that DTS uses less compression thus providing marginally better sound.

DTS is less widespread than Dolby Digital.

THX Surround EX

THX Surround EX takes the Dolby Digital signal and creates another additional matrixed channel, which is then sent to one or two surround speakers, thus giving a 6.1 or 7.1 sound.

SDDS

The latest entry in cinema digital sound, Sony Dynamic Digital Sound® (SDDS)

It boasts five separate channels at the front of the theater as well as left and right surround channels, for a total of eight available channels including the subwoofer.

Applications

Cinema and Soundtracks.

Creation of audio environment for different purposes.

Integrate voice-based comments in an archeological site or monument.

Video Game Consoles.

Personal Computers.

Enhanced situation awareness in military and public safety applications.

Conclusion

Today's surround sound experience is the result of decades of evolution. The surround sound experience is now easily accessible, practical, and affordable for the consumer. Go get surrounded..!!!

References

Technical Document AESTD1001.0.01-05 multichannel surround sound systems and operation

HDMI Transceivers Simplify the Design of Home Theater Systems by Ian Beavers, Joe Triggs, and Lie Dou, Volume 45 – February 2011

“Understanding Home Theatre”, Curt Robbins, 2015 edition.

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