During the first few years when movies started to be made available to the public, only visual images are available for the viewers to appreciate. Synchronised sound tracks do not yet company any movies back then. Thus, the label “silent era” films for movies made during this period. To compensate for the lack of sound, a number of studios released features with accompanying sheet music scores that allow pianists to play along as the film is shown.
Film viewing has been typified like this until the late 1920s. By then a number of studios had already developed films with synchronised sound tracks and had started to have these films shown on theatres. But then, however, such synchronisation is still unrefined. Nonetheless, as viewing films with synchronised sounds is definitely an even better experience than just the video with an accompanying music, the general public quickly adjusted to this new form of motion films.
Today, that’s history. Thanks to the latest technology in both the movie and sound industry, movie viewing had been a lot more fulfilling. Standardisation of common multi-channel formats, however, took place only in the 1960s when Ray Dolby, then a new engineer with Ampex corporation, created a method for recording multi-channel sound visually into a motion film. This technology functions well in both the old stereo movie theatres, as well as in the new “Dolby Stereo” four-channel surround sound theatres.
Dolby Digital (DD), also known as Dolby AC-3 (audio coding 3) is the surround sound standard in home theatres today. By around the middle of the 1990’s, DD technology has become available for home theater use by regular users. This made the home theatre experience even more enjoyable. With the existing surround sound device, a common family TV room can now produce a one of a kind home theatre experience for just about everyone. Making various multiple audio tracks to “surround” the movie watching and/or music listening audience, will make them imagine that they are a part of the action happening in front of them. With the surround sound system, the viewers will hear sounds coming from all around them, making them completely captivated by the home theatre experience that there will come a point that they are no longer aware of their physical surroundings.
Dolby Digital surround sound setup runs up to five distinct channels (center, left, right, surround left, surround right) of maximum frequency effects (from 20 Hz to 20,000 Hz), and an optional sixth channel reserved for low frequency effects (LFE), like that projected by a subwoofer speaker. The LFE channel provides Dolby Digital the “.1″ label. It signifies that the sixth channel is not full frequency, as it contains only deep bass runs (3 Hz to 120 Hz).