Audio Engineering Society

Chicago Section

Meeting Review, November 6, 2003


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11/6/03 Meeting Highlights
by Tom Miller

On November 6, Tomlinson Holman gave a presentation on the History and Future of Surround Sound.  The meeting took place after the group enjoyed a dinner at the Holiday Inn.

 

Mr. Holman in informal discussion with Chicago AES members

 

Mr Holman presented the history of surround sound as an Opera in many acts, with each era of surround sound being an act.  Mr. Holman traced the history of surround sound from its beginnings centuries ago in antiphonal choirs and organs.  He described the history of multi-channel reproduction systems, from the 1933 Bell labs demonstrations using 3-channel telephony through current 10.2 channel experiments at TMH labs.

 

Mr. Holman outlined the technical capabilities of past film sound formats, including Fantasound, Cinerama, Cinemascope, Todd AO, and several analog Dolby formats on 35 and 70 mm film.  He provided informative and often amusing descriptions of the rise and fall of these formats.  He described the rationale behind the selection of 5.1 discreet channels for digital film audio, and how this has been extended to 6.1 and 7.1 channels through the use of matrixing.  He also described the history of multi-channel sound for home, from early 4 channel analog matrixed sound on LP to current surround sound digital formats available on DVD.

 

He then went on to describe the rationale behind expanding the number of channels beyond the currently popular 5.1 format.  He explained that using additional bits to increase the bandwidth, sample rate or the number of bits per channel beyond current standards provides little or no demonstrable improvement in audio quality.  However, using these same extra bits to increase the number of channels makes an easily perceptible improvement, even to untrained listeners.  Mr. Holman explained that it is nearly impossible to ever have enough channels for full transparency.  Further increases in the number of channels will continue to provide improvements in realism. 

 

Specific shortcomings of the existing 5.1 channel system include poor side images, poor sense of envelopment - especially at low frequencies, poor rear center imaging, and no vertical information.  A system with more channels would address these problems, but could still be down-mixed to be compatible with current systems having fewer channels.  Data to control the down mix can be included with the music data, resulting in a scalable system.

 

The thorough presentation was followed both with a brief question and answer session for the full group and then many small group informal discussions.