■Encode/Decode
When a signal or other information is processed, compressed and digitized, this is called encoding. Encoding can be used to record an extremely large amount of information on a single CD or DVD.
An encoded signal cannot be listened to directly. It must be returned to its original state (i.e. audible sound) and this is called decoding.
■Sound field
Not all sound travels from the sound source directly into the human ear, but instead reflects off of walls, ceilings and other objects to arrive at the ear slightly delayed (early reflection). It may also reflect repeatedly in a complicated manner before reaching the ear (subsequent reverberation). A human is able to perceive the size and shape of a location based on the various sounds heard in this way. The specific acoustic space of a particular building is called a sound field.
■Dolby Surround
In movie theaters and in live theaters, the spectators are surrounded by many speakers and sound effects geared to each scene are used to make sound move from front to back and right to left. This gives the sound a three dimensional feel that surrounds the entire body. Dolby Surround is used to implement this realistic effect. Originally, the Dolby Surround system consisted of a total of four channels: two front channels (right and left), one center channel, and one rear channel. Later, two-channel stereo compatibility was added to for broadcast and video media used in the home. The ability to easily set up a home AV system capable of stereo reproduction is one of the biggest features of Dolby Surround.
■Dolby Digital
Dolby Digital consists of a total of five channels: three front channels (left, center and right) and two rear channels (right and left), plus a distinct LFE channel for low frequency effect. It is therefore commonly referred to as a 5.1 channel system. Using digital compression technology for all 5.1 channels, Dolby Digital can be used for completely independent audio reproduction. Dolby Digital offers superior sound separation between each channels and a more three dimensional surround effect in comparison to the older Dolby Surround, which mixes four channels (three front and one rear) into two-channel stereo and separates them using a matrix circuit.
■DTS (Digital Theater Systems)
Digital Surround
DTS was developed to replace the analog soundtracks of movies with six discrete channels of digital soundtracks, and it is now installed in many theaters around the world. The DTS digital playback system changed the way we experienced movies in theaters with six discrete channels of superb digital audio.
DTS technology, through intense research and development has made it possible to deliver similar encode/decode discrete technology to home audio surround-sound entertainment.
DTS Digital Surround is an encode/decode system which delivers six channels of master-quality, 20-bit audio; technically, it is 5.1 channels, which means 5 full-range (left, center, right and two surround) channels, plus a subwoofer (LFE) channel (as “ 0.1” ). It is compatible with the 5.1 speaker configurations that are currently available for home theater systems.
■Virtual surround
We basically perceive the direction from which sounds come to us based on the difference in time they reach the right and left ears and differences in sound level. Virtual technology is based on this property of the human ear. A DSP (digital sound field processor — a form of digital signal processing) and right and left main speakers are used so that the listener feels like he or she is hearing sounds that come from virtual speakers located in directions other than just the two physical speakers. This allows the listener to experience surround effects as if rear speakers were present as in a five-speaker system.
■YAMAHA DSP (Digital Sound Field
Processor)
YAMAHA technicians traveled to world famous concert halls, opera houses and other locations just to measure acoustical information such as the direction, intensity, band characteristics, and delay time of reflected sounds. This wealth of information was then put on a ROM.
Using a built-in YAMAHA DSP (digital sound field processor) to create sound fields, this unit allows you to freely select various sound field programs created from this actual acoustical data so that you can reproduce the sound field of concert halls and live houses right in your listening room.
Movie makers design sounds for a movie so that the sound and screen become one. Dialog is positioned right on the screen, sound effects behind the screen, music behind that, and surround effects wrap around the audience.
CINEMA DSP is a program for use in AV reproduction that has evolved from YAMAHA DSP. Fusing the movie sound decoders, Dolby Pro Logic, Dolby Digital and DTS, with YAMAHA DSP, allows you to reproduce the type of surround sound field of the quality found on a dubbing stage designed to optimize movie surround conditions. (A dubbing stage is the final mix used to complete the final sound design for a movie.)
By adding YAMAHA DSP processing to both the right and left front channels and the center channel, the CINEMA DSP program wraps the audience in a surround sound field that not only makes dialog real, but penetrates and surrounds the screen to give depth to sound effects and music as well as a smooth sense of movement to sound sources.
