The Importance of Audio

Films are produced using three types of sounds: human voices from different directions and angles, background music and enhanced sound effects. These are crucial to making a movie realistic for the audience.  Those of us in this generation have seen audio/video technology growing so fast that it has been hard to keep up. We all have seen how audio effects can change a simple scene to a thriller. “Half the magic of storytelling is in the sound.”

History of sound in movies:  Till 1927 all movies were silent with no sound, followed by movies with live piano sound. The first movie sound recorded was for ”The Jazz Singer” in  analog mono signal which was called the talkies.  Next was the introduction of stereo sound  recorded on movie film. Stereo recording uses two channels, where two microphones are placed relative to the sound source to record simultaneously. The two channels will have distinct time-of-arrival information. During playback, the listener’s brain uses those subtle differences in timing to triangulate the positions of the recorded objects. 

To provide a surround sound effect Dolby Prologic processing was introduced in movies where the audience can hear the center and surround channels. The first commercial motion picture with stereophonic sound was Walt Disney’s Fantasia, released in November 1940.

With the introduction of digital sound higher clarity was achieved 5.1 surround sound (Left, Right , Center , Left Surround,  Right surround and low frequency effects ) was used in the 1975 film Tommy. 

Compressed sound is used in movies for higher clarity. Dolby AC3, DTS, SDDS and MPEG II are some formats introduced in DVD movies. To bring the theatre effect into the home, home theatre products were introduced in the  market. 5.1 / 7.1 channels provide 360°  sound effects  and sound clarity is further improved using lossless coding.  

Eventually movie makers found they were unable to provide the height and special effects in the vertical field. To recreate rain , flight take off  and other  vertical moving effects immersive sound codecs were invented. In basic terms, production technology has gone from being surround, meaning the sound coming from level positions around the listener (left, right, front, and back), to being immersive or “3D.” This means that the sound can now come from above or below, at any point, opening up a new, dynamic audio field. 

 Immersive Sound

The film “The Impossible”, directed by Juan Antonio Bayona and starring Ewan McGregor and Naomi Watts, recreates the drama of the tsunami that hit the coastlines of Thailand in December 2004 using immersive sound that allowed the audience to become completely involved in the story. Object-based surround sound allows sounds to travel not just on the flat plane, but adds height information within the area the dome occupies. Object-based surround codecs include Auro 3D (Barco, Inc.), DTS:X (DTS, Inc.), Dolby Atmos (Dolby Laboratories, Inc.) and MPEG-H. 

Dolby Atmos is the most common of these with nearly 6,400 installations worldwide (Few hundred theatres in India). It is not limited to any particular speaker setup. An immersive audio album recorded and produced in Dolby Atmos can be played back using up to 64 speakersAtmos introduced object-based audio and several technological advancements that brought some principles from interactive environment into the movie industry. Combination of channel-based audio (beds) and object audio (objects). 

  • Channel-based configuration (bed) is 7.1.4 (7.1 configuration plus four  elevated ceiling channels). 
  • Object audio (objects) – possibility of placing sounds in x-y-z coordinates  360° Surround sound rendering . 
  • Up to 128 lossless audio streams for delivery format (7.1.4 bed plus  objects) reproduced with (up to) 64 speakers, 
  • Side surround speakers start at the screen allowing full 360° panning of objects 

DOLBY ATMOS Home theatre Speaker setup

An audio video receiver will receive audio/video information from  Blu-ray players, set top boxes, Streaming  like NETFLIX, Prime, Disney + and HBO Max. Multichannel audio is decoded and processed for output to available speakers, Lip Sync(or karaoke),  audio enhancement or cinema modes. AV receivers supports multiple decoders and post processing for audio.  Recreating the original sound will be important for high end products

Surround sound adds a different dimension to the experience in a home theatre or media room. Now, Auro-3D, DTS:X, MPEG H and Dolby Atmos formats force us to rethink the standard in surround sound by adding height information to really immerse us into another world.

Immersive audio system would ideally create three levels of sound as shown in the diagram: surround layer, height layer and top layer (“Voice of God” layer).  The speaker locations are 11.1(11 referring to the number of speakers that can be connected and 1 the number of sub-woofers), 13.1, 15.1 and the super high end home theatres are looking to support 31.1  speakers. 

In the diagram you can see that the surround layer is the ground layer in the 13.1 configuration, based on the room size we can have one or two subwoofers.

While viewing a movie, a gun sound can come from one angle, footsteps can seem to approach from another by panning the sound between speakers, you can give the illusion of something moving around in the room with you. Therefore they call it ‘immersive.’ The sound gives an extra dynamic allowing you to experience the full story at the very best image and audio quality that one can get inside a cinema, in the comfort of your home”  User experience is highly important  for today’s generation, who want the same sound effects in all devices like smart phones and tablets like Ipads. These days headphones are designed to give 360° surround sound effects for personal enjoyment


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