If you may have watched HD movies or playing games in high definition or waited while a movie began in the home theatres, you may have noticed a sign that flashes across the big screen, read as Dolby Digital.
That is the technology that enables the audience to have a real-like cinematic experience while sitting at a home theater, and also by creating a theatre experience just at home.
A Brief Context
The Surround Sound system is a technique developed by Dolby Laboratories in 1976, used for enriching the quality and depth of audio by using more than one audio channel emanating from the speakers that surround the listener. We call these surround channels. It was first used in the movie theatres, which can go back to the 1940 musical by Walt Disney called “Fantasia.”
Prior to the invention of the concept of surround sound, the sound systems at theatres had three channels of sound which played from three different loudspeakers placed at the (left, the center, and the right, located in front of the audience, towards the direction of the screen).
The surround sound added more than one channel that produced sounds from loudspeakers to the side or at the rear of the listener, which created the sensation of the audio coming from a horizontal direction, or the x-axis around the listener.
The surround sound formats have quite a wide range in recording and reproduction methods, along with the positioning and number of additional channels.
The commercial surround sound systems include DVDs, videocassettes, the DVD-Audio (DVD-A), and the Super Audio CD (SACD) formats. Cinema may use the 5.1 surround sound format which includes Dolby Digital and the DTS (Digital Theatre Sounds).
Sound localization is the listener’s ability to identify the location, direction, and the origin of a sound in any direction and from any distance.
This quality of the sound, which the human ear is adept at determining the distance, direction, and depth of, is achieved by using multiple audio channels originating from multiple loudspeakers.
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Surround sound started as an experimental technology in the 1930s for the enhancement of audio technologies. Walt Disney, with his timeless musical Fantasia, brought this technology to mainstream entertainment in 1940.
Later Disney’s team of sound engineers developed what was known as the “Fantasound,” an audio system for the audience at the theatres, which could deliver on the same lines the vibrant visuals in Fantasia did.
By the 1950s, Hollywood developed more affordable multichannel sound systems to go with their Cinerama widescreen, which was not very economical for the businesses either.
The concept turned into a full-fledged technology called the Surround Sound, making a huge comeback in 1975 with the introduction of Dolby Stereo, created by the Dolby Laboratories.
It enabled audio effects and ambient noises that felt very real and gave a pristine experience to the audience.
Movies like the Star Wars franchise and Apocalypse Now adopted surround sound technology to deliver an immersive experience to the audience.
The Dolby Laboratories expanded the technology further by introducing the 5 and later the 7 channel supporting systems.
Companies like Digital Theater Systems (DTS) and Sony Dynamic Digital Sound joined the market while advancing the technology much further.
The real Surround Sound was released in 1982 with Dolby Surround Technology. It could recreate the cinematic sounds of Dolby Stereo at home, what eventually came to be known as the home theatre.
The virtual surround sound is thus a true example of human ingenuity and the advancement of technology in the world of audio engineering.
The Surround Sound technology is that which carefully tricks the human ears into believing that a sound that emanates by digital sound projection is, in reality, originating from what is called a 5.1 channel.
To break down the nomenclature, 5 is the number that refers to the number of speakers and 1 is the number of the subwoofer. Surround Sound can be created by capturing the source of sound from the front and the back, generated through software, based on Hyungen’s Principle.
The surround sound systems usually have a specific listener location (which is called the sweet spot) where the most optimal audio effects are experienced. The sweet spot presents a fixed or a forward perspective of the sound field.
This advancement in audio technique enhances the reception and understanding, the perception of the spatialization of the audio sounds by exploiting the sound localization.
The advancement in the fields of psychoacoustics led to such creations, psychoacoustics being the study of sound perception.
A typical surround sound setup consists of four channels, the front left, front right, a center mid, and a channel for the sides and back. The last channel can be separated as rear left and rear right.
Different aspects of the sounds are output via different channels. The dialogue could be output through the middle channel whereas the ambient noises are delivered by other channels.
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Types of Surround Sound System
There are different configurations in channels available in the surround sound system.
2.0 Speaker System: This system has two speakers one on the right and another on the left of the device or the television.
This system does not contain a subwoofer, whereas the 2.1 system has one subwoofer which enhances the audio experience for the user, though it is a basic setup, to begin with.
3.1 Speaker System: This has four channels, three speakers, and one subwoofer.
5.1 Surround Sound System: This is a home theater system that is the most widely used. It consists of 6 channels, 5 speakers and 1 subwoofer.
7.1 and 7.1.2 Surround Sound System: The 7.1 speakers consist of 8 channels, 7 speakers, and 1 subwoofer, whereas the 7.1.2 system consists of all of the given implements in the 7.1 system with the addition of 2 ceiling speakers.
Thus, the invention of the Surround Sound changed the landscape of audio perception and use in the fields of entertainment.
Companies like Dolby Digital, SONY, Audyssey, DTS to name a few have created remarkable differences in the home theatre and theatre scenario, which continues to give an immaculate experience to the user.
It gives a much greater sound quality than the stereo system with its use of multiple audio channels and the speakers around the listener.