Surround sound

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16.2 channel surround sound Sound-10 2.svg
16.2 channel surround sound

Surround sound is a technique for enriching the fidelity and depth of sound reproduction by using multiple audio channels from speakers that surround the listener (surround channels). Its first application was in movie theaters. Prior to surround sound, theater sound systems commonly had three "screen channels" of sound that played from three loudspeakers (left, center, and right) located in front of the audience. Surround sound adds one or more channels from loudspeakers to the side or behind the listener that are able to create the sensation of sound coming from any horizontal direction (at ground level) around the listener.

Contents

Surround sound formats vary in reproduction and recording methods, along with the number and positioning of additional channels. The most common surround sound specification, the ITU's 5.1 standard, calls for 6 speakers: Center (C), in front of the listener; Left (L) and Right (R), at angles of 60°; Left Surround (LS) and Right Surround (RS) at angles of 100–120°; and a subwoofer, whose position is not critical.

Surround sound typically has a listener location (sweet spot) where the audio effects work best, and presents a fixed or forward perspective of the sound field to the listener at this location. The technique enhances the perception of sound spatialization by exploiting sound localization: a listener's ability to identify the location or origin of a detected sound in direction and distance. This is achieved by using multiple discrete audio channels routed to an array of loudspeakers. [1]

Fields of application

Though cinema and soundtracks represent the major uses of surround techniques, its scope of application is broader than that as surround sound permits creation of an audio-environment for all sorts of purposes. Multichannel audio techniques may be used to reproduce contents as varied as music, speech, natural or synthetic sounds for cinema, television, broadcasting, or computers. In terms of music content for example, a live performance may use multichannel techniques in the context of an open-air concert, of a musical theatre performance or for broadcasting; [2] for a film, specific techniques are adapted to movie theater or to home (e.g. home cinema systems). [3] [4] The narrative space is also a content that can be enhanced through multichannel techniques. This applies mainly to cinema narratives, for example the speech of the characters of a film, [5] [6] [7] but may also be applied to plays performed in a theatre, to a conference, or to integrate voice-based comments in an archeological site or monument. For example, an exhibition may be enhanced with topical ambient sound of water, birds, train or machine noise. Topical natural sounds may also be used in educational applications. [8] Other fields of application include video game consoles, personal computers and other platforms. [9] [10] [11] [12] In such applications, the content would typically be synthetic noise produced by the computer device in interaction with its user. Significant work has also been done using surround sound for enhanced situation awareness in military and public safety application. [13]

Types of media and technologies

Commercial surround sound media include videocassettes, DVDs, and SDTV broadcasts encoded as compressed Dolby Digital and DTS, and lossless audio such as DTS HD Master Audio and Dolby TrueHD on HDTV Blu-ray Disc and HD DVD, which are identical to the studio master. Other commercial formats include the competing DVD-Audio (DVD-A) and Super Audio CD (SACD) formats, and MP3 Surround. Cinema 5.1 surround formats include Dolby Digital and DTS. Sony Dynamic Digital Sound (SDDS) is an 8 channel cinema configuration which features 5 independent audio channels across the front with two independent surround channels, and a Low-frequency effects channel. Traditional 7.1 surround speaker configuration introduces two additional rear speakers to the conventional 5.1 arrangement, for a total of four surround channels and three front channels, to create a more 360° sound field.

Most surround sound recordings are created by film production companies or video game producers; however some consumer camcorders have such capability either built-in or available separately. Surround sound technologies can also be used in music to enable new methods of artistic expression. After the failure of quadraphonic audio in the 1970s, multichannel music has slowly been reintroduced since 1999 with the help of SACD and DVD-Audio formats. Some AV receivers, stereophonic systems, and computer sound cards contain integral digital signal processors or digital audio processors to simulate surround sound from a stereophonic source (see fake stereo).

In 1967, the rock group Pink Floyd performed the first-ever surround sound concert at "Games for May", a lavish affair at London’s Queen Elizabeth Hall where the band debuted its custom-made quadraphonic speaker system. [14] The control device they had made, the Azimuth Co-ordinator, is now displayed at London's Victoria and Albert Museum, as part of their Theatre Collections gallery. [15]

History

The first documented use of surround sound was in 1940, for the Disney studio's animated film Fantasia . Walt Disney was inspired by Nikolai Rimsky-Korsakov's operatic piece Flight of the Bumblebee to have a bumblebee featured in his musical Fantasia and also sound as if it was flying in all parts of the theatre. The initial multichannel audio application was called 'Fantasound', comprising three audio channels and speakers. The sound was diffused throughout the cinema, controlled by an engineer using some 54 loudspeakers. The surround sound was achieved using the sum and the difference of the phase of the sound. However, this experimental use of surround sound was excluded from the film in later showings. In 1952, "surround sound" successfully reappeared with the film "This is Cinerama", using discrete seven-channel sound, and the race to develop other surround sound methods took off. [16] [17]

In the 1950s, the German composer Karlheinz Stockhausen experimented with and produced ground-breaking electronic compositions such as Gesang der Jünglinge and Kontakte , the latter using fully discrete and rotating quadraphonic sounds generated with industrial electronic equipment in Herbert Eimert's studio at the Westdeutscher Rundfunk (WDR). Edgar Varese's Poème électronique, created for the Iannis Xenakis-designed Philips Pavilion at the 1958 Brussels World's Fair, also used spatial audio with 425 loudspeakers used to move sound throughout the pavilion.

In 1957, working with artist Jordan Belson, Henry Jacobs produced Vortex: Experiments in Sound and Light - a series of concerts featuring new music, including some of Jacobs' own, and that of Karlheinz Stockhausen, and many others - taking place in the Morrison Planetarium in Golden Gate Park, San Francisco. Sound designers commonly regard this as the origin of the (now standard) concept of "surround sound." The program was popular, and Jacobs and Belson were invited to reproduce it at the 1958 World Expo in Brussels. [18] There are also many other composers that created ground-breaking surround sound works in the same time period.

In 1978, a concept devised by Max Bell for Dolby Laboratories called "split surround" was tested with the movie Superman . This led to the 70mm stereo surround release of Apocalypse Now , which became one of the first formal releases in cinemas with three channels in the front and two in the rear. [19] There were typically five speakers behind the screens of 70mm-capable cinemas, but only the Left, Center and Right were used full-frequency, while Center-Left and Center-Right were only used for bass-frequencies (as it is currently common). The Apocalypse Now encoder/decoder was designed by Michael Karagosian, also for Dolby Laboratories. The surround mix was produced by an Oscar-winning crew led by Walter Murch for American Zoetrope. The format was also deployed in 1982 with the stereo surround release of Blade Runner .

The 5.1 version of surround sound originated in 1987 at the famous French Cabaret Moulin Rouge. A French engineer, Dominique Bertrand used a mixing board specially designed in cooperation with Solid State Logic, based on 5000 series and including six channels. Respectively: A left, B right, C centre, D left rear, E right rear, F bass. The same engineer had already achieved a 3.1 system in 1974, for the International Summit of Francophone States in Dakar, Senegal.

Creating surround sound

Surround sound is created in several ways. The first and simplest method is using a surround sound recording technique—capturing two distinct stereo images, one for the front and one for the back or by using a dedicated setup, e.g. an augmented Decca tree [20] —or mixing-in surround sound for playback on an audio system using speakers encircling the listener to play audio from different directions. A second approach is processing the audio with psychoacoustic sound localization methods to simulate a two-dimensional (2-D) sound field with headphones. A third approach, based on Huygens' principle, attempts reconstructing the recorded sound field wave fronts within the listening space; an "audio hologram" form. One form, wave field synthesis (WFS), produces a sound field with an even error field over the entire area. Commercial WFS systems, currently marketed by companies sonic emotion and Iosono , require many loudspeakers and significant computing power. The 4th approach is using three mics, one for front, one for side and one for rear, also called Double MS recording.

The Ambisonics form, also based on Huygens' principle, gives an exact sound reconstruction at the central point; however, it is less accurate away from the central point. There are many free and commercial software programs available for Ambisonics, which dominates most of the consumer market, especially musicians using electronic and computer music. Moreover, Ambisonics products are the standard in surround sound hardware sold by Meridian Audio. In its simplest form, Ambisonics consumes few resources, however this is not true for recent developments, such as Near Field Compensated Higher Order Ambisonics. [21] Some years ago it was shown that, in the limit, WFS and Ambisonics converge. [22]

Finally, surround sound can also be achieved by mastering level, from stereophonic sources as with Penteo, which uses digital signal processing analysis of a stereo recording to parse out individual sounds to component panorama positions, then positions them, accordingly, into a five-channel field. However, there are more ways to create surround sound out of stereo, for instance with the routines based on QS and SQ for encoding Quad sound, where instruments were divided over 4 speakers in the studio. This way of creating surround with software routines is normally referred to as "upmixing", [23] which was particularly successful on the Sansui QSD-series decoders that had a mode where it mapped the L ↔ R stereo onto an ∩ arc.[ citation needed ]

Standard configurations

There are many alternative setups available for a surround sound experience, with a 3-2 (3 front, 2 back speakers and a Low Frequency Effects channel) configuration (more commonly referred to as 5.1 surround) being the standard for most surround sound applications, including cinema, television and consumer applications. [24] This is a compromise between the ideal image creation of a room and that of practicality and compatibility with two-channel stereo. [25] Because most surround sound mixes are produced for 5.1 surround (6 channels), larger setups require matrixes or processors to feed the additional speakers. [25]

The standard surround setup consists of three front speakers LCR (left, center and right), two surround speakers LS and RS (left and right surround respectively) and a subwoofer for the Low Frequency Effects (LFE) channel, that is low-pass filtered at 120 Hz. The angles between the speakers have been standardized by the ITU (International Telecommunication Union) recommendation 775 and AES (Audio Engineering Society) as follows: 60 degrees between the L and R channels (allows for two-channel stereo compatibility) with the center speaker directly in front of the listener. The Surround channels are placed 100-120 degrees from the center channel, with the subwoofer's positioning not being critical due to the low directional factor of frequencies below 120 Hz. [26] The ITU standard also allows for additional surround speakers, that need to be distributed evenly between 60 and 150 degrees. [24] [26]

Surround mixes of more or fewer channels are acceptable, if they are compatible, as described by the ITU-R BS. 775-1, with 5.1 surround. The 3-1 channel setup (consisting of one monophonic surround channel) is such a case, where both LS and RS are fed by the monophonic signal at an attenuated level of -3 dB. [25]

The function of the center channel is to anchor the signal so that any central panned images do not shift when a listener is moving or is sitting away from the sweet spot. [27] The center channel also prevents any timbral modifications from occurring, which is typical for 2-channel stereo, due to phase differences at the two ears of a listener. [24] The centre channel is especially used in films and television, with dialogue primarily feeding the center channel. [25] The function of the center channel can either be of a monophonic nature (as with dialogue) or it can be used in combination with the left and right channels for true three-channel stereo. Motion Pictures tend to use the center channel for monophonic purposes with stereo being reserved purely for the left and right channels. Surround microphones techniques have however been developed that fully use the potential of three-channel stereo.

In 5.1 surround, phantom images between the front speakers are quite accurate, with images towards the back and especially to the sides being unstable. [24] [25] The localisation of a virtual source, based on level differences between two loudspeakers to the side of a listener, shows great inconsistency across the standardised 5.1 setup, also being largely affected by movement away from the reference position. 5.1 surround is therefore limited in its ability to convey 3D sound, making the surround channels more appropriate for ambience or effects. [24] )

7.1 channel surround is another setup, most commonly used in large cinemas, that is compatible with 5.1 surround, though it is not stated in the ITU-standards. 7.1 channel surround adds two additional channels, center-left (CL) and center-right (CR) to the 5.1 surround setup, with the speakers situated 15 degrees off centre from the listener. [24] This convention is used to cover an increased angle between the front loudspeakers as a product of a larger screen.

Surround microphone techniques

Most 2-channel stereophonic microphone techniques are compatible with a 3-channel setup (LCR), as many of these techniques already contain a center microphone or microphone pair. Microphone techniques for LCR should, however, try to obtain greater channel separation to prevent conflicting phantom images between L/C and L/R for example. [25] [27] [28] Specialised techniques have therefore been developed for 3-channel stereo. Surround microphone techniques largely depend on the setup used, therefore being biased towards the 5.1 surround setup, as this is the standard. [24]

Surround recording techniques can be differentiated into those that use single arrays of microphones placed in close proximity, and those treating front and rear channels with separate arrays. [24] [26] Close arrays present more accurate phantom images, whereas separate treatment of rear channels is usually used for ambience. [26] For accurate depiction of an acoustic environment, such as a halls, side reflections are essential. Appropriate microphone techniques should therefore be used, if room impression is important. Although the reproduction of side images are very unstable in the 5.1 surround setup, room impressions can still be accurately presented. [25]

Some microphone techniques used for coverage of three front channels, include double-stereo techniques, INA-3 (Ideal Cardioid Arrangement), the Decca Tree setup and the OCT (Optimum Cardioid Triangle). [25] [28] Surround techniques are largely based on 3-channel techniques with additional microphones used for the surround channels. A distinguishing factor for the pickup of the front channels in surround is that less reverberation should be picked up, as the surround microphones will be responsible for the pickup of reverberation. [24] Cardioid, hypercardioid, or supercardioid polar patterns will therefore often replace omnidirectional polar patterns for surround recordings. To compensate for the lost low-end of directional (pressure gradient) microphones, additional omnidirectional (pressure microphones), exhibiting an extended low-end response, can be added. The microphone's output is usually low-pass filtered. [25] [28] A simple surround microphone configuration involves the use of a front array in combination with two backward-facing omnidirectional room microphones placed about 10–15 meters away from the front array. If echoes are notable, the front array can be delayed appropriately. Alternatively, backward facing cardioid microphones can be placed closer to the front array for a similar reverberation pickup. [26]

The INA-5 (Ideal Cardioid Arrangement) is a surround microphone array that uses five cardioid microphones resembling the angles of the standardised surround loudspeaker configuration defined by the ITU Rec. 775. [26] Dimensions between the front three microphone as well as the polar patterns of the microphones can be changed for different pickup angles and ambient response. [24] This technique therefore allows for great flexibility.

A well established microphone array is the Fukada Tree, which is a modified variant of the Decca Tree stereo technique. The array consists of five spaced cardioid microphones, three front microphones resembling a Decca Tree and two surround microphones. Two additional omnidirectional outriggers can be added to enlarge the perceived size of the orchestra or to better integrate the front and surround channels. [24] [25] The L, R, LS and RS microphones should be placed in a square formation, with L/R and LS/RS angled at 45 degrees and 135 degrees from the center microphone respectively. Spacing between these microphones should be about 1.8 meters. This square formation is responsible for the room impressions. The center channel is placed a meter in front of the L and R channels, producing a strong center image. The surround microphones are usually placed at the critical distance (where the direct and reverberant field is equal), with the full array usually situated several meters above and behind the conductor. [24] [25]

The NHK (Japanese broadcasting company) developed an alternative technique also involving five cardioid microphones. Here a baffle is used for separation between the front left and right channels, which are 30 cm apart. [24] Outrigger omnidirectional microphones, low-pass filtered at 250 Hz, are spaced 3 meters apart in line with the L and R cardioids. These compensate for the bass roll-off of the cardioid microphones and also add expansiveness. [27] A 3-meter spaced microphone pair, situated 2–3 meters behind front array, is used for the surround channels. [24] The centre channel is again placed slightly forward, with the L/R and LS/RS again angled at 45 and 135 degrees respectively.

The OCT-Surround (Optimum Cardioid Triangle-Surround) microphone array is an augmented technique of the stereo OCT technique using the same front array with added surround microphones.The front array is designed for minimum crosstalk, with the front left and right microphones having supercardioid polar patterns and angled at 90 degrees relative to the center microphone. [24] [25] It is important that high quality small diaphragm microphones are used for the L and R channels to reduce off-axis coloration. [26] Equalization can also be used to flatten the response of the supercardioid microphones to signals coming in at up to about 30 degrees from the front of the array. [24] The center channel is placed slightly forward. The surround microphones are backwards facing cardioid microphones, that are placed 40 cm back from the L and R microphones. The L, R, LS and RS microphones pick up early reflections from both the sides and the back of an acoustic venue, therefore giving significant room impressions. [25] Spacing between the L and R microphones can be varied to obtain the required stereo width. [25]

Specialized microphone arrays have been developed for recording purely the ambience of a space. These arrays are used in combination with suitable front arrays, or can be added to above mentioned surround techniques. [26] The Hamasaki square (also proposed by NHK) is a well established microphone array used for the pickup of hall ambience. Four figure-eight microphones are arranged in a square, ideally placed far away and high up in the hall. Spacing between the microphones should be between 1–3 meters. [25] The microphones nulls (zero pickup point) are set to face the main sound source with positive polarities outward facing, therefore very effectively minimizing the direct sound pickup as well as echoes from the back of the hall [26] The back two microphones are mixed to the surround channels, with the front two channels being mixed in combination with the front array into L and R.

Another ambient technique is the IRT (Institut für Rundfunktechnik) cross. Here, four cardioid microphones, 90 degrees relative to one another, are placed in square formation, separated by 21–25 cm. [26] [28] The front two microphones should be positioned 45 degrees off axis from the sound source. This technique therefore resembles back to back near-coincident stereo pairs. The microphones outputs are fed to the L, R and LS, RS channels. The disadvantage of this approach is that direct sound pickup is quite significant.

Many recordings do not require pickup of side reflections. For Live Pop music concerts a more appropriate array for the pickup of ambience is the cardioid trapezium. [25] All four cardioid microphones are backward facing and angled at 60 degrees from one another, therefore similar to a semi-circle. This is effective for the pickup of audience and ambience.

All the above-mentioned microphone arrays take up considerable space, making them quite ineffective for field recordings. In this respect, the double MS (Mid Side) technique is quite advantageous. This array uses back to back cardioid microphones, one facing forward, the other backwards, combined with either one or two figure-eight microphone. Different channels are obtained by sum and difference of the figure-eight and cardioid patterns. [25] [26] When using only one figure-eight microphone, the double MS technique is extremely compact and therefore also perfectly compatible with monophonic playback. This technique also allows for postproduction changes of the pickup angle.

Bass management

Surround replay systems may make use of bass management, the fundamental principle of which is that bass content in the incoming signal, irrespective of channel, should be directed only to loudspeakers capable of handling it, whether the latter are the main system loudspeakers or one or more special low-frequency speakers called subwoofers.

There is a notation difference before and after the bass management system. Before the bass management system there is a Low Frequency Effects (LFE) channel. After the bass management system there is a subwoofer signal. A common misunderstanding is the belief that the LFE channel is the "subwoofer channel". The bass management system may direct bass to one or more subwoofers (if present) from any channel, not just from the LFE channel. Also, if there is no subwoofer speaker present then the bass management system can direct the LFE channel to one or more of the main speakers.

Low frequency effects (LFE) channel

Because the low-frequency effects channel requires only a fraction of the bandwidth of the other audio channels, it is referred to as the ".1" channel; for example "5.1" or "7.1".[ citation needed ]

The LFE channel is a source of some confusion in surround sound. It was originally developed to carry extremely low "sub-bass" cinematic sound effects (with commercial subwoofers sometimes going down to 30 Hz, e.g., the loud rumble of thunder or explosions) on their own channel. This allowed theaters to control the volume of these effects to suit the particular cinema's acoustic environment and sound reproduction system. Independent control of the sub-bass effects also reduced the problem of intermodulation distortion in analog movie sound reproduction. A "sub-woofer" capable of playing back frequencies as low as 5 Hz was developed by a small speaker manufacturer in Florida. It used a propellor design and required a large cabinet to move sub-sonic air mass. [29]

In the original movie theater implementation, the LFE was a separate channel fed to one or more subwoofers. Home replay systems, however, may not have a separate subwoofer, so modern home surround decoders and systems often include a bass management system that allows bass on any channel (main or LFE) to be fed only to the loudspeakers that can handle low-frequency signals. The salient point here is that the LFE channel is not the "subwoofer channel"; there may be no subwoofer and, if there is, it may be handling a good deal more than effects. [30]

Some record labels such as Telarc and Chesky have argued that LFE channels are not needed in a modern digital multichannel entertainment system.[ citation needed ] They argue that all available channels have a full-frequency range and, as such, there is no need for an LFE in surround music production, because all the frequencies are available in all the main channels. These labels sometimes use the LFE channel to carry a height channel, underlining its redundancy for its original purpose. The label BIS generally uses a 5.0 channel mix.

Channel notation

Channel notation indicates the number of discrete channels encoded in the audio signal, not necessarily the number of channels reproduced for playback. The number of playback channels can be increased by using matrix decoding. The number of playback channels may also differ from the number of speakers used to reproduce them if one or more channels drives a group of speakers. Notation represents the number of channels, not the number of speakers.

The first digit in "5.1" is the number of full range channels. The ".1" reflects the limited frequency range of the LFE channel.

For example, two stereo speakers with no LFE channel = 2.0
5 full-range channels + 1 LFE channel = 5.1

An alternative notation shows the number of full-range channels in front of the listener, separated by a slash from the number of full-range channels beside or behind the listener, with a decimal point marking the number of limited-range LFE channels.

E.g. 3 front channels + 2 side channels + an LFE channel = 3/2.1

The notation can be expanded to include Matrix Decoders. Dolby Digital EX, for example, has a sixth full-range channel incorporated into the two rear channels with a matrix. This is expressed:

3 front channels + 2 rear channels + 3 channels reproduced in the rear in total + 1 LFE channel = 3/2:3.1

The term stereo, although popularised in reference to two channel audio, historically also referred to surround sound, as it strictly means "solid" (three-dimensional) sound. However this is no longer common usage and "stereo sound" almost exclusively means two channels, left and right.

Channel identification

In accordance with ANSI/CEA-863-A [31]

ANSI/CEA-863-A identification for surround sound channels
Zero-based channel indexChannel nameColor-coding on commercial
receiver and cabling
MP3/WAV/FLAC
[32] [33] [34] [35]
DTS/AAC
[36]
Vorbis/Opus
[37] [38]
010Front LeftWhite
122Front RightRed
201CenterGreen
357Subwoofer FrequencyPurple
433Rear LeftBlue
544Rear RightGrey
665Alternative Rear LeftBrown
776Alternative Rear RightKhaki
Diagram
Front LeftCenterFront Right
Rear LeftRear Right
Alternative Rear LeftAlternative Rear Right
Subwoofer Frequency

Height channels

IndexChannel nameColor-coding on commercial
receiver and cabling
8Left height 1Yellow
9Right height 1Orange
10Left height 2Pink
11Right height 2Magenta

Sonic Whole Overhead Sound

In 2002, Dolby premiered a master of We Were Soldiers which featured a Sonic Whole Overhead Sound soundtrack. This mix included a new ceiling-mounted height channel.

Ambisonics

Ambisonics is a recording and playback technique using multichannel mixing that can be used live or in the studio and which recreates the soundfield as it existed in the space, in contrast to traditional surround systems, which can only create illusion of the soundfield if the listener is located in a very narrow sweetspot between speakers. Any number of speakers in any physical arrangement can be used to recreate a sound field. With 6 or more speakers arranged around a listener, a 3-dimensional ("periphonic", or full-sphere) sound field can be presented. Ambisonics was invented by Michael Gerzon.

Binaural recording

Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create the 3-D stereo experience of being present in the room with the performers or instruments. The idea of a three dimensional or "internal" form of sound has developed into technology for stethoscopes creating "in-head" acoustics and IMAX movies creating a three dimensional acoustic experience.

Panor-Ambiophonic (PanAmbio) 4.0/4.1

PanAmbio combines a stereo dipole and crosstalk cancellation in front and a second set behind the listener (total of four speakers) for 360° 2D surround reproduction. Four channel recordings, especially those containing binaural cues, create speaker-binaural surround sound. 5.1 channel recordings, including movie DVDs, are compatible by mixing C-channel content to the front speaker pair. 6.1 can be played by mixing SC to the back pair.

Standard speaker channels

Several speaker configurations are commonly used for consumer equipment. The order and identifiers are those specified for the channel mask in the standard uncompressed WAV file format (which contains a raw multichannel PCM stream) and are used according to the same specification for most PC connectible digital sound hardware and PC operating systems capable of handling multiple channels. [39] [40] While it is possible to build any speaker configuration, there is little commercial movie or music content for alternative speaker configurations. However, source channels can be remixed for the speaker channels using a matrix table specifying how much of each content channel is played through each speaker channel.

Standard speaker channels
Channel nameIDIdentifierIndexFlag
Front LeftFLSPEAKER_FRONT_LEFT00x00000001
Front RightFRSPEAKER_FRONT_RIGHT10x00000002
Front CenterFCSPEAKER_FRONT_CENTER20x00000004
Low FrequencyLFESPEAKER_LOW_FREQUENCY30x00000008
Back LeftBLSPEAKER_BACK_LEFT40x00000010
Back RightBRSPEAKER_BACK_RIGHT50x00000020
Front Left of CenterFLCSPEAKER_FRONT_LEFT_OF_CENTER60x00000040
Front Right of CenterFRCSPEAKER_FRONT_RIGHT_OF_CENTER70x00000080
Back CenterBCSPEAKER_BACK_CENTER80x00000100
Side LeftSLSPEAKER_SIDE_LEFT90x00000200
Side RightSRSPEAKER_SIDE_RIGHT100x00000400
Top CenterTCSPEAKER_TOP_CENTER110x00000800
Front Left HeightTFLSPEAKER_TOP_FRONT_LEFT120x00001000
Front Center HeightTFCSPEAKER_TOP_FRONT_CENTER130x00002000
Front Right HeightTFRSPEAKER_TOP_FRONT_RIGHT140x00004000
Rear Left HeightTBLSPEAKER_TOP_BACK_LEFT150x00008000
Rear Center HeightTBCSPEAKER_TOP_BACK_CENTER160x00010000
Rear Right HeightTBRSPEAKER_TOP_BACK_RIGHT170x00020000

Most channel configuration may include a low frequency effects (LFE) channel (the channel played through the subwoofer.) This makes the configuration ".1" instead of ".0". Most modern multichannel mixes contain one LFE, some use two.

Standard speaker channel layouts
IconSystemChannelsLFEFrontSidesBack
FL+FRFCFLC+FRCTFL+TFRSL+SRBL+BRBCTBL+TBR
1 0 channels (mono) label.svg Mono [Note 1] 1.0NoNoYesNoNoNoNoNoNo
2 1 channels (stereo subwoofer) label.svg Stereo [Note 2] 2.02.1YesNoNoNoNoNoNoNo
3 0 channels (stereo front-center) label.svg Stereo3.03.1YesYesNoNoNoNoNoNo
2 0-1 channels (dolby surround) label.svg Surround3.0NoYesNoNoNoNoNoYesNo
4 0 channels (quadrophonic)(quadrophonie) label.svg Quad4.0NoYesNoNoNoNoYesNoNo
4 0 channels side quad.svg Side Quad4.0NoYesNoNoNoYesNoNoNo
4 1channel.svg Surround4.04.1YesYesNoNoNoNoYesNo
5 1 channels (surround sound) label.svg (Front)5.05.1YesYesNoNoNoYesNoNo
5 1 channels side.svg Side [Note 3] 5.05.1YesYesNoNoYesNoNoNo
5 1 4 channels atmos.svg Atmos [Note 4] 5.1.4YesYesYesNoYesNoYesNoYes
6 1 channels (extended surround sound) label.svg Hexagonal (Back)6.06.1YesYesNoNoNoYesYesNo
Front6.06.1YesYesYesNoNoNoYesNo
6 1 channels surround sound.svg (Side)6.06.1YesYesNoNoYesNoYesNo
7 1 channels (extended surround sound SDDS) label.svg Wide7.1YesYesYesYesNoNoYesNoNo
Side [Note 3] 7.07.1YesYesYesNoYesNoNoNo
7 1 channels surround sound.svg Surround [Note 5] 7.07.1YesYesNoNoYesYesNoNo
7 1 4 channels atmos.svg Atmos [Note 4] 7.1.4YesYesYesNoYesYesYesNoYes
Octagonal8.0NoYesYesNoNoYesYesYesNo
9 1 channels surround sound alternate 2.svg Surround9.09.1YesYesNoYesYesYesNoNo
Surround11.011.1YesYesYesYesYesYesNoNo
11 1 4 channels atmos.svg Atmos [Note 4] 11.1.4YesYesYesYesNoTwo per sideTwo per sideYesYes

7.1 surround sound

7.1 surround sound is a popular format in theaters & Home cinema including Blu-rays with Dolby and DTS being major players. [41]

7.1.2/7.1.4 immersive sound

7.1.2 and 7.1.4 immersive sound along with 5.1.2 and 5.1.4 format adds either 2 or 4 overhead speakers to enable sound objects and special effect sounds to be panned overhead for the listener. Introduced for theatrical film releases in 2012 by Dolby Laboratories under the trademark name Dolby Atmos. [42]

10.2 surround sound

10.2 is the surround sound format developed by THX creator Tomlinson Holman of TMH Labs and University of Southern California (schools of Cinema/Television and Engineering). Developed along with Chris Kyriakakis of the USC Viterbi School of Engineering, 10.2 refers to the format's promotional slogan: "Twice as good as 5.1". Advocates of 10.2 argue that it is the audio equivalent of IMAX.[ weasel words ]

11.1 surround sound

11.1 sound is supported by BARCO with installations in theaters worldwide. [43]

22.2 surround sound

22.2 is the surround sound component of Ultra High Definition Television, developed by NHK Science & Technical Research Laboratories. As its name suggests, it uses 24 speakers. These are arranged in three layers: A middle layer of ten speakers, an upper layer of nine speakers, and a lower layer of three speakers and two sub-woofers. The system was demonstrated at Expo 2005, Aichi, Japan, the NAB Shows 2006 and 2009, Las Vegas, and the IBC trade shows 2006 and 2008, Amsterdam, Netherlands.

See also

Notes

  1. For historical reasons, when using (1.0) mono sound, often in technical implementations the first (left) channel is used, instead of the center speaker channel, in many other cases when playing back multichannel content on a device with a mono speaker configuration all channels are downmixed into one channel. The way standard mono and stereo plugs used for common audio devices are designed ensures this as well.
  2. Stereo (2.0) is still the most common format for music, as most computers, television sets and portable audio players only feature two speakers, and the red book Audio CD standard used for retail distribution of music only allows for two channels. A 2.1 speaker set does generally not have a separate physical channel for the low-frequency effects, as the speaker set downmixes the low-frequency components of the two stereo channels into one channel for the subwoofer.
  3. 1 2 THX 5.1 Surround Sound Speaker set-up Archived 2010-05-28 at the Wayback Machine . This is the correct speaker placement for 5.0/6.0/7.0 channel sound reproduction for Dolby and Digital Theater Systems.
  4. 1 2 3 Setup Guides for Your Home
  5. "Sony Print Master Guidelines" (PDF). Archived from the original (PDF) on 2012-03-07This plus an LFE is the correct speaker placement for 8-track Sony Dynamic Digital Sound.CS1 maint: postscript (link)

Related Research Articles

Subwoofer Loudspeaker designed to reproduce low-pitched audio frequencies

A subwoofer is a loudspeaker designed to reproduce low-pitched audio frequencies known as bass and sub-bass, lower in frequency than those which can be (optimally) generated by a woofer. The typical frequency range for a subwoofer is about 20–200 Hz for consumer products, below 100 Hz for professional live sound, and below 80 Hz in THX-certified systems. Subwoofers are never used alone, as they are intended to augment the low-frequency range of loudspeakers that cover the higher frequency bands. While the term "subwoofer" technically only refers to the speaker driver, in common parlance, the term often refers to a subwoofer driver mounted in a speaker enclosure (cabinet), often with a built-in amplifier.

Dolby Digital, originally synonymous with Dolby AC-3, is the name for what has now become a family of audio compression technologies developed by Dolby Laboratories. Originally named Dolby Stereo Digital until 1995, except for Dolby TrueHD, the audio compression is lossy, based on the modified discrete cosine transform (MDCT) algorithm. The first use of Dolby Digital was to provide digital sound in cinemas from 35 mm film prints; today, it is now also used for applications such as TV broadcast, radio broadcast via satellite, digital video streaming, DVDs, Blu-ray discs and game consoles.

Ambisonics Full-sphere surround sound format

Ambisonics is a full-sphere surround sound format: in addition to the horizontal plane, it covers sound sources above and below the listener.

The low-frequency effects (LFE) channel is a band-limited audio track that is used for reproducing deep and intense low-frequency sounds in the 3–120 Hz frequency range.

Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround. Dolby Stereo was developed by Dolby in 1976 for analog cinema sound systems. The format was adapted for home use in 1982 as Dolby Surround when HiFi capable consumer VCRs were introduced. It was further improved with the Pro Logic decoding system in 1987.

5.1 surround sound Sound systems that use 5 speakers and one subwoofer

5.1 surround sound is the common name for surround sound audio systems. 5.1 is the most commonly used layout in home theatres. It uses five full bandwidth channels and one low-frequency effects channel. Dolby Digital, Dolby Pro Logic II, DTS, SDDS, and THX are all common 5.1 systems. 5.1 is also the standard surround sound audio component of digital broadcast and music.

Matrix decoding is an audio technology where a small number of discrete audio channels are decoded into a larger number of channels on play back. The channels are generally, but not always, arranged for transmission or recording by an encoder, and decoded for playback by a decoder. The function is to allow multichannel audio, such as quadraphonic sound or surround sound to be encoded in a stereo signal, and thus played back as stereo on stereo equipment, and as surround on surround equipment – this is "compatible" multichannel audio.

3D audio effects are a group of sound effects that manipulate the sound produced by stereo speakers, surround-sound speakers, speaker-arrays, or headphones. This frequently involves the virtual placement of sound sources anywhere in three-dimensional space, including behind, above or below the listener.

Stereophonic sound Method of sound reproduction using two audio channels

Stereophonic sound or, more commonly, stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two or more independent audio channels through a configuration of two or more loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing. Thus the term "stereophonic" applies to so-called "quadraphonic" and "surround-sound" systems as well as the more common two-channel, two-speaker systems. Stereo sound has been in common use since the 1970s in entertainment media such as broadcast radio, TV, recorded music, internet, computer audio, and cinema.

DTS (sound system) series of multichannel audio technologies

DTS, Inc. is an American company that makes multichannel audio technologies for film and video. Based in Calabasas, California, the company introduced its DTS technology in 1993 as a competitor to Dolby Laboratories, incorporating DTS in the film Jurassic Park (1993). The DTS product is used in surround sound formats for both commercial/theatrical and consumer-grade applications. It was known as The Digital Experience until 1995. DTS licenses its technologies to consumer electronics manufacturers.

7.1 surround sound Sound systems that use 7 speakers and one subwoofer

7.1 surround sound is the common name for an eight-channel surround audio system commonly used in home theatre configurations. It adds two additional speakers to the more conventional six-channel (5.1) audio configuration. As with 5.1 surround sound, 7.1 surround sound positional audio uses the standard front left and right, center, and LFE (subwoofer) speaker configuration. However, whereas a 5.1 surround sound system combines both surround and rear channel effects into two channels, a 7.1 surround system splits the surround and rear channel information into four distinct channels, in which sound effects are directed to left and right surround channels, plus two rear surround channels.

Microphone practice

There are a number of well-developed microphone techniques used for recording musical, film, or voice sources or picking up sounds aa part of sound reinforcement systems. The choice of technique depends on a number of factors, including:

Bass management

The fundamental principle of bass management in surround sound replay systems is that bass content in the incoming signal, irrespective of channel, should be directed only to loudspeakers capable of reproducing it, whether the latter are the main system loudspeakers or one or more special low-frequency speakers (subwoofers). There are notation differences between the pre-bass-managed signal and after it has passed through the bass manager. For example, when using 5.1 surround sound:

Ambisonic UHJ format is a development of the Ambisonic surround sound system designed to be compatible with mono and stereo media. It is a hierarchy of systems in which the recorded soundfield will be reproduced with a degree of accuracy that varies according to the available channels. Although UHJ permits the use of up to four channels, only the 2-channel variant is in current use. In Ambisonics, UHJ is also known as "C-Format".

Lipinski Sound

Lipinski Sound is a professional market and audiophile oriented manufacturer of loudspeakers, subwoofers, powered speaker stands, surround sound systems, power amplifiers, microphones, and microphone preamplifiers.

Ambiophonics is a method in the public domain that employs digital signal processing (DSP) and two loudspeakers directly in front of the listener in order to improve reproduction of stereophonic and 5.1 surround sound for music, movies, and games in home theaters, gaming PCs, workstations, or studio monitoring applications. First implemented using mechanical means in 1986, today a number of hardware and VST plug-in makers offer Ambiophonic DSP. Ambiophonics eliminates crosstalk inherent in the conventional “stereo triangle” speaker placement, and thereby generates a speaker-binaural soundfield that emulates headphone-binaural sound, and creates for the listener improved perception of “reality” of recorded auditory scenes. A second speaker pair can be added in back in order to enable 360° surround sound reproduction. Additional surround speakers may be used for hall ambience, including height, if desired.

Audio mixing (recorded music)

In sound recording and reproduction, audio mixing is the process of optimizing and combining multitrack recordings into a final mono, stereo or surround sound product. In the process of combining the separate tracks, their relative levels are adjusted and balanced and various processes such as equalization and compression are commonly applied to individual tracks, groups of tracks, and the overall mix. In stereo and surround sound mixing, the placement of the tracks within the stereo field are adjusted and balanced. Audio mixing techniques and approaches vary widely and have a significant influence on the final product.

The sweet spot is a term used by audiophiles and recording engineers to describe the focal point between two speakers, where an individual is fully capable of hearing the stereo audio mix the way it was intended to be heard by the mixer. The sweet spot is the location which creates an equilateral triangle together with the stereo loudspeakers. In the case of surround sound, this is the focal point between four or more speakers, i.e., the location at which all wave fronts arrive simultaneously. In international recommendations the sweet spot is referred to as "reference listening point".

The design of speaker systems for Ambisonic playback is governed by several constraints:

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