The future of Surround Sound

The Soundfield Microphone

The Soundfield Microphone

The July 2009 issue of the U.S. Stereophile magazine contains a leading editorial by Steve Guttenberg in recognition of the tenth anniversary of the launch of Super Audio CD (SACD). He begins:

“I love stereo, always have, always will. A great stereo recording can produce such a full-bodied, three-dimensional soundstage that surround sound seems superfluous. Multichannel is just peachy for home theater, but good ‘ol stereo suits music just fine, thanks very much.”

I am not sure what Mr. Guttenberg’s definition of “three-dimensional” is, but I can accept one of those given by Princeton University’s Wordnet: “giving the illusion of depth”. (Let’s not imagine that two loudspeakers in the same horizontal plane can give the impression of height!)

Stereoscopic vision, gives the impression of depth (in the sense of distance), by employing two channels. But the use of two channels in stereo audio recordings does not achieve any comparable result. The illusion of depth is created in audio recording by including reverberation (natural or artificial) on distant sounds. Two channels are not required: many excellent monophonic recordings achieve this — for instance, the amazing 78s of Wagner’s Parsifal from the 1927 Bayreuth Festival.

I have heard and made surround sound recordings and I prefer them to stereo because they give me a better impression of “being there”, rather than listening to the music through a large hole in the wall.

Nowadays quite a few concert halls use large reverberation chambers behind the stage to “enhance” their natural acoustics. The effect of the chambers can be varied by opening and closing the doors that connect them to the hall. Symphony Hall in Birmingham, England, has chambers of 12,700 cubic metres that can be used, wholly or partially, to increase the apparent volume of the hall and add a noticeable amount of reverberation to the music.

The only problem is that the reverberation does not surround the listener, since it emanates from outside the part of the hall where the audience sits. The impression I have in Birmingham is that the reverberation comes from behind the orchestra, as it does on stereo recordings, in which reverberation picked up from behind the microphones is laid over the music. By contrast, when I hear a concert in a traditional concert hall, such as Vienna’s Großer Musikvereinsaal, I am surrounded by reverberation and my ears tell me that I am in the same room as the performers.

When a stereo recording is played back, the images of the music and the reverberation both come from behind the line joining the two loudpeakers, and I fear that audiences may have become so used to listening to stereo recordings that they expect to hear the same effect in the concert hall. This may explain the success of the Birmingham hall and others like it, though the concept seems backwards to me.

All audio recordings rely on an illusion. They are a substitute for the live music that they seek to emulate, and need all the help they can get to sound anything like the real thing. In the long run, impoverishing the experience of live music-making to make it match more closely its “canned” substitute is not going to impress. A surround sound recording has the power to immerse the listener in the acoustic in which the music was performed, removing some of the barriers still encountered in stereo between the listener and the music itself. Such an increase in realism must be more attractive than the two-dimensional experience provided by stereo — even though the recording is still an illusion and a substitute for the real thing.

It is very disappointing that a writer in Stereophile magazine, which also has a regular feature called Music in the Round should be so negative about the future of surround sound for the reproduction of music in the home. Nearly 60 years ago there was similar pessimism about stereo. (See the official BBC position of 1950 reproduced in the letter I sent to Stereophile in 2001.)

I believe that most music benefits from recording in coherent surround sound, of which Ambisonics is the most highly developed system. Ambisonic recordings can be reproduced in the horizontal plane with a minimum of four loudspeakers, though with more of them it is possible to extend this to the vertical plane also. Indeed, it is probably true to say that the more channels the better — except for the cost. If we can overcome this economic barrier, without destroying the planet, we should be able to transmit and store more channels and position the loudspeakers in less rigid positions than today. Surround sound would then be accepted as the norm — as stereo is today — and nobody would think of denigrating it.

In the not too distant future (SA)CDs and DVDs will be replaced by magnetic or electronic storage with no moving parts beyond electrons. In the meantime, there are some interesting and enjoyable suround sound recordings being made by several companies, of which I will mention only a few. For jazz you may wish to investigate Chesky Records, while classical music is recorded by Pentatone Classics. You can read about the philosophy of this Dutch company here. Tacet in Germany is another interesting company. They often offer alternative mixes of their recordings: one conventional, and another that positions the players around the listener. Their series of Moving Real Surround Sound is a creative and interesting development that you can read about on their website. Other companies are also making exciting surround sound recordings: I encourage you to explore them.

I have written more about surround sound and some of my own experiments here.


© David Pickett and davidpickett, 2009. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to David Pickett and davidpickett with appropriate and specific direction to the original content

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