Outline
Sound recording technology has continued to advance in the recent past. The quality of sound produced by a set of speakers is being enhanced using modern technology of recording. Music that could only be recorded in the studios is now being recorded at home by simply following certain criteria. The storage capacity of the systems has also been enhanced and with a small device known as a DVD, many pieces of both audio and visual sounds can be easily recorded and stored. The technology has not yet reached its peak and many more inventions are being done to make the surround sound system
The entertainment industry has received a lot of attention from the masses all over the world. This business has thus been greatly enhanced over the years to produce more quality results. The commercial purposes of this industry have been expanded and there is a demand for more sophisticated systems to enhance sound production. The recording systems that were earlier used to record live music into lesser portable devices, was not efficient. The sound was either not clearer, or some materials were lost during the recording process. This problem has however been solved and it has been possible to not only record and listen to a song as it was originally but also better sounds can be enhanced using the surround system.
Surround system is a technique that involves different mechanisms of producing sound. This is usually achieved by mixing different sounds to come up with a definite rhythm. The sounds produced may be naturally recorded or mechanically invented and stored up in a sound system. For quality listening, a listener is supposed to receive the sound in three dimensions. The multichannel surround technology ensures that the three-dimensional hearing of a human being is achieved which includes the right, left, and back surround. This technology can be used for commercial purposes like theaters and for personal entertainment at home (Rumsey, 2006). Surround recordings are mostly done by the film industries and the producers of video games. Since the emergence of the digital world, surround sound has become of high quality due to the invention of sound cards in computers and stereophonic systems.
Surround sound may be created in several different ways according to the number of systems available and the sound quality desired. In the simplest form of all, the sound is created using the microphone technique; here the speakers are joined to an audio system. The performer will then be able to play and listen to different sounds while in different directions. In a second way, with the help of psychoacoustic sound localization, headphones are used to enhance the two-dimensional sound field of the listener. Using the Huygens principle, sound may also be created with an audio hologram where the wave field synthesis produces sound over a certain area. Surround sound may also be achieved by mastering the different sound sources like the stereophonic, the parse out individual recording, and the positions of the component panorama. Once the positions are established, they are re-channeled accordingly. The surround sound system works by connecting each channel to a speaker, using the matrix system the contents of the channel are applied to the speakers. Depending on the strength of the signal, the information transmitted may be of a greater or lesser extent.
In transmitting the sound to the speakers, the bass sound has to be well managed; the speakers used should have the capacity to handle the same in order to achieve quality results. If the main system speakers are not compliant, the subwoofers may be used. With the base management system, the bass sound may be transmitted to a number of subwoofers from any channel or to the speakers. The low-frequency effects channel was mainly developed for the sub-bass cinema sound like thunder and explosions. This technique enables the theaters to adjust the effect of the bass to fit in their sound systems. To enhance the technology for home replay, a modern home surround decoder has bass management that will enable the bass sound on any channel to be transmitted to the speakers that have the capacity to handle the signals.
Surround sound specifications are the distinction between the number of channels available on the main signal and the channels produced during playback. It may also be the number of channels reproduced and the number of speakers that have been used to transmit the sound. To enhance this frequency, matrix decoding may be used to decode the sound in the required form. Notation can simply be described by numbers using the position of the listener (William, 1998). These numbers are separated by a slash where the first number before the slash represents the channels in the front and the other number after the slash, those that are behind or beside the listener, and a decimal to represent the number of LFE channels. For example, a notation 5/3.2 means that there are five channels in front of the listener, three at the side, and two LFE channels. This simple notation may also be expanded into a matrix decoder with more range channels incorporated into it.
There are different forms of channel surrounds that are distinguished according to the number and positions of the channels and speakers. The first surround channel is the Dolby surround. This channel is capable of extracting three audio channels encoded from a source that has two channels. (Bartlett, 2005 p.20) states that, âThere are two channels which are directed to the speakers in front, one is placed at the right, the other at the left and the third channel at the rear surroundâ. This system uses a total of three speakers which must be identical. They are placed around the same distance as the listener. In the case of two rear speakers, then they should be placed above the height of the ear but behind the listening position.
The second one is quadraphonic, this surround channel has four audio channels encoded from a source of either two or four sources. Two channels are placed at the front, one at the left and the other at the right. The other two channels are placed at the rear sound, one at the left and the other at the right. A total of four speakers are used which should be placed at a 45 degrees listening angle above the height of the ear.
The third surround channel is the Dolby pro logic. This channel involves four audio channels encoded from a channel that has two sources. Two channels are for the speakers located at the front, where one is placed right and the other one at the left. Another channel is placed at the center and the remaining one is left for both speakers at the rear mono surround. A total of five speakers are used in this arrangement. The speakers in the front are placed at the edges of the screen adjacent to the listener and the tweeters are positioned at the ear height. The central speakers are placed behind or under the TV screen and should be closer to the ear. For the surround speakers, they should be behind the listening position and above ear height with the construction of a bi-pole.
The fourth channel surround is the Dolby pro logic II, here; five audio channels are extracted from two encoded channels or a stereo source. Two channels are for the speakers located in the front, one for the speakers is placed at the center and the remaining two at the rear surround area. This surround sound is also referred to as 3-2 stereo due to the position of the speakers. The speakers are arranged according to the standards of ITU, these standards require that the left and right speakers be located at an angle of 30 degrees and the rear ones at 110 degrees position. However, it has been suggested that, when the rear speakers are placed at 150 degree position, a better sound effect shall be produced. (Bartlett, 2005)
The other channel surround is the analog magnetic. This channel is capable of delivering six audio channels from a channel that has six sources. In this arrangement, four channels for the speakers are placed at the front, one at the left, the other at the left center, the third at the right center and the last one at the right. One of the remaining two channels is placed at the center and the other at the rear monaural surround.
The next channel surround is a kind of analog magnetic called the Dolby stereo âbaby boomâ. This surround channel delivers five audio channels and a low frequency effect (LFE) channel from six sources. Two channels are directed to the speakers at the front, another one for the speaker at the center and the remaining two for the surround speakers at the rear and an additional LFE channel.
Next, we have a Dolby digital, DTS, SDDS, Penteo that delivers five discrete audio channels and an LFE channel from a six channel source. Two channels are directed to the speakers at the front, one channel for the speaker at the center, two for the surround speakers at the rear position and one LFE. The position of the speakers is similar to that in Dolby pro logic II in accordance with the ITU standards.
The other one is the Dolby pro logic IIx. Six audio channels are extracted from a low frequency channel with a two channel source or a stereo. For the arrangement of the channels, two are for the speakers positioned in front, one directed to the speaker at the center and two are for the surround speakers placed at the sides. One is for the surround speakers placed at the rear on the back side and one low frequency channel for the sub woofer. The speakers in front are positioned at the edge of the screen facing the listener. The central speakers should be behind or under the projector and screen respectively. The speakers on the sides should be left and right of the listener at a similar distance with the front and the rear speakers (Rumsey, 2006). The rear channel speakers are behind the position of listening with a construction that is of high quality monopolar. The speakers in front should be placed at the ear height while the surround ones should be above.
The other surround channel is the Dolby digital EX. This surround channel is capable of delivering five audio channels, an extracted channel and a LFE channel from six sources. Two discrete channels are for the speakers in the front, a discrete channel for the speaker at the center, two channels for the surround speakers at the sides, a channel for the surround speaker at the rear back and a an LFE channel. The arrangement and position of the speakers in this case is similar to that in Dolby pro logic IIx.
The next is the DTS-ES that delivers six discrete audio channels and an LFE from seven sources. Two for the speakers at the front, one for the speaker at the center, two for the surround speakers at the sides, one for the sound speaker at the rear and an LFE. Speakers in this case are also arranged in the same position as those in Dolby pro logic IIx.
Cinerama 7 track that delivers seven audio channels from seven sources and in arranging them, four channels are for the speakers at the front, one channel for the center, and the other two channels that can be switched. One channel could be on the left and right and the other on the rear could feed the one at the right and the left. The first speakers in this case are placed across the wall but should either be on top or behind the screen. The three surround channels should be put at the left, on the right and on the rear walls.
The other one is the Dolby digital plus, DTS-HD, Dolby true HD. This one delivers seven audio channels and an LFE channel to eight sources. Two channels are for the speakers at the front, one for the speaker at the center, two for surround speakers at the sides, two for the speakers at the rear and one LFE. In case of a wide screen cinema, the above will be arranged as; four channels for the speakers at the front, one channel for the speaker at the center, two for surround speakers at the rear and an LFE channel. The front speakers are placed at the edges of the screen facing the listener and the tweeters are to be placed at an ear height (Bartlett, 2005). The central speakers are placed behind the projector or under the TV screen but close to the ear height. The side channel speakers are put to the left and to the right, occupying a similar distance with the front and the rear speakers. Rear channel speakers are put on the side walls but behind the listener and should have a high-quality monopolar.
The 10.2 is a surround sound format that is twice that of 5.1. It has the capacity to handle fourteen discrete channels where there are five front speakers, five surround channels, two LFE channels and two height channels. The 22.2 channel surround us an ultra high definition video. This system has twenty four speakers that are arranged in three layers. The lower layer has three speakers, the middle one ten and the upper one nine. According to the bass management of the system, the speakers on the right hand side will use the subwoofer on the left and the speakers on the right will use the subwoofer on the right. The surround speakers at the center and back are divided equally among the two subwoofers. Apart from enhancing the sound production, the two subwoofers also act as low frequency effect channels. (Bartlett, 2005)
Ambisonics
Ambisonics is a technology that was developed by Michael Gerzon for the purpose of using multichannel technology of mixing for recording and replay. Using this technology, more than six speakers can be arranged around the listener to produce a periphonic sound. It is a modern technology that has helped to solve the problems of the quadraphonic system. What was not possible with the traditional system has been transformed and music can be played using more than six speakers. PanAmbio uses a total of four speakers to produce a two dimensional sound, in the first combination, a stereo dipole and a cross talk cancellation are placed in front and the other set placed at the back. Four channel recordings in this system are used to create a binaural surround sound. In the traditional system, quality sound was not produced as most of it was sucked by the speakers. There was also a definite arrangement that this sound system had to follow yet some vocals were not clear.
The modern Ambisonics system has a number of advantages that make it the best among the other systems; the system requires only a total of four channels yet it produces full surround with a height periphony, The speakers must not be placed in the common square position, any convenient position may be used, images of the piece may appear at any place rather than the position of the speaker, it brings out the effect needed for any number of channels due to the compatible hierarchical encoding scheme that transmits Ambisonics material through channels. This makes it best for use by DVDs; the UHJ undecoded two-channel produces super stereo effects, the surround sound images of this system are not affected by the position of the listener.
Setting up a studio for surround sound
With advanced technology, it is now possible for an individual to set up a surround sound recording system. Using the knowledge that one has on the surround system, he can use the facilities on the computer to create a quality sound system. To begin with, the following elements are required; a surround encoder, a surround decoder, an eight by eight audio interface, a sequencer, a DVD burning software, a DVDR recorder, five speakers and a subwoofer and a mixer which is optional.
Two systems, one for the studio creation and the playback can be created. The first play back system may be placed in the sitting room and will compose of the DVDs and a sound receiver and the second one will be for the studio which will have monitors connected to the mixer or an audio interface. A hard ware mixer will enhance the procedure if it has not less than six discrete outputs. In the first step, six busses are placed in the mixer, one at the center, another in the subwoofer, the other at the right, left, rear left and the last on at the rear right (Klinger, 2006) These busses will send the sound directly to the speakers and the audio interface.
In the second step, the hardware mixer is routed out to the inputs of audio interface. With the aux sends any channel signal can be send in variable amounts to the six streams at an individualsâ convenience. Alternatively subgroups out may be used to direct the full signal of the channels. In the third step the software mixer is routed back to the audio interface using the six busses created (Mollison, 2003).
During the creation process, the tracks are made in a similar way as a stereo mix. When a mixer and a software are used in the sequencer through the audio interface, the midi tracks can be auditioned anywhere in surround matrix. With the help of software monitoring, the midi tracks are tweaked with the plugging effect of the sequencer until that time when the song is ready to be encoded. As one wishes, many busses may be created to get the desired output. Vocals can also be positioned to the five speakers; there is always a slight delay to the left, a pitch shift to the right and a harmonizer at the back.
A surround panner can be used in the application to position the elements where they blend well. Every track may be assigned a surround panner that is different. At the end of the process, the application rendering facility is used to come up with six mono audio files for the speakers. When it comes to the encoding process a different application should be used. The encoder will transform the six files into one file that is recognized by the Dolby digital surround file. The main purpose of encoding is to surround files in that instead of having only two tracks, one will have six. (Klinger, 2006)
During the burning process, an application that allows a DVD burning is necessary so as to set the menu structure of the DVD for the music to be easily selected using a remote control. Texts and images usually appear on the screen just like on the web, by carefully following the links, the desired piece of music is selected and then played. The link will lead to two file options, a video file that is in MPEG format and the audio one in an AC3 file. At this point an individual can add as many songs as per the capacity of the DVD. After this process, the DVD is ready for burning. After burning the DVD, it needs to be tested to find out if the process was successful. When all the procedure is followed, the music is supposed to sound just like it sounds when played in the studio. If the surround receiver being used has a listen mode, then it will be sensitive to the Dolby digital sound track in the mix and subsequently switch it to a Dolby digital play back. To avoid going through the digital audio converter, the digital output of the player should be used directly to the receiver of the digital input. (Mollison, 2003)
Studio technology
With the common use of multi channel surround and stereo audio materials, the use of this sources need to be managed appropriately so as to facilitate the process of recording, broadcasting and production. This need has been intensively addressed by the studio technology using surround model 76 and 77 control console. The system is simple and powerful to use to the following features that are accessible; the channel mute and solo, the down mix and the reference level. It also has digital audio inputs and analogue outputs to enhance quality recording. Using contemporary technology and observation of the design practices, you will get the best quality audio system.
Model 76 central controllers is the beginning point for surround system, studiocomm. It occupies a very minimal space and connects three stereo and two surround inputs alongside stereo and surround monitor outputs (Adams, 2001). There are digital signals that are not well balanced, they are however present broadcast and post production environments. They make use of the BNC connectors. They directly support sample rates of up to 192 kHz and 24 bit depth. Monitor outputs are balanced line level with a power up and power down protection circuit to protect the connected loud speakers.
Nine BNC connectors are used to connect model 76 with the help of digital audio signals. A 25 pin subminiature connector is used to make the signals of analog monitor. To supply power to the unit, a flash based micro controller that is of advanced nature is used. There are two transformers in the system that perform distinct functions, a 9-pin D-subminiature connector joins model 76 to a maximum of four model 77 control consoles. The second transformer is a 9-pin âD-subâ connector that connects the signals of the remote control to the model 76.
The 77 control console in mainly located at the operators place because it the central place for the command. Using the tip of a finger, it is possible to select any monitoring function. There are numerous led indicators that display the complete information about its status (Mollison, 2003). Compared to the model 77 control console, model 76 central controllers can handle up to four out put levels. With this technology, multiple users are able to control the monitoring system. A model 77 will connect to a model 76 using a 9-pin cable. The main advantage of the model 77 is that it has the ability to constitute several operating parameters in the software control.
Conclusion
With this technology at hand, sound production has been enhanced at a greater extend. Storage devices that can handle a large capacity of music and decode them as per the convenience of the listener have also been invented. Depending on the mood of the listener he or she can adjust the sound system to play the music in a particular design. A small device known as a remote control makes it possible for an individual to enhance the format of the system and easily change it to suit a certain standard. Such technology has just marked the beginning of more advances that are being made. At this rate, we may not know what to expect next. We hope that inventions will be made to ensure that maximum production of quality sound will be automatically produced without having to observe a certain order. Everything will be programmed using the computer technology and we will only need to press some few buttons and everything will be set. (Mollison, 2003)
References
Adams J. Build your own home theater: Newnes, 2001 pp 30-35.
Bartlett J. Practical recording techniques: Focal Press, 2005 pp18-23.
Klinger B. Beyond the multiplex: University of California Press, 2006 pp 16-21.
Mollison M. Producing Videos: Allen & Unwin, 2003 pp 33-37.
Rumsey F. Sound and recording: Focal Press, 2006 pp 10-16.
William G. 3-D audio using loudspeakers: Springer, 1998 pp 23-29.