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SLAPBACK: (noun) the echo of a sound as it bounces between parallel reflective walls.

Digital Musings

How constant is sound? It’s a key question in trying to mark out the difference between analog and digital sound. As I’ve mentioned before (see Analog lives, F/T October 1999), discussions on the nature of the difference usually start out with the accepted definitions of analog and digital recording. In the real world, sound is a constant signal, which is captured, unbroken, on magnetic tape during analog sound recording. Digital recording, on the other hand, doesn’t make a continuous record of a sound but instead takes thousands of samples of the sound per second. To the ear, these samples blend together to produce the illusion of uninterrupted sound.

This is the accepted thinking regarding the differences between analog and digital, but are these assumptions valid? To digress on a totally unscientific path, I have often wondered about how "constant" our everyday world is.

When in Las Vegas for the Audio Engineers Society (AES) convention last year, I visited the "Race for Atlantis" 3-D animated IMAX film at Caesar's. This is billed as a ride as well as a movie since the entire platform that you sit on dips, dives and moves in sync with picture. There are 60 speakers behind the IMAX screen and a couple built into the 3-D headsets. The experience of this animated battle to save Atlantis is totally believable - 3-D audio, 3-D film and G forces make the experience seat-of-the-pants real, the suspension of disbelief instantaneous.

Yet this experience, except for the physical chair movements, was created from separate bits and pieces. The film was not constant - total darkness alternated with perfectly still pictures to create the moving image. The sound was not constant - it was a string of digital samples with spaces between each sample. It was possible to convince the audience that they were taking part in this experience because our eyes, ears and brains are easily fooled. The implication here, to me, is that perhaps our other senses are just as easily fooled. Perhaps what we perceive as a constant reality is something other than constant.

If the "Race for Atlantis" illusion can be created so convincingly by a species that has only been playing with film images and sound for 100 years or so, what could a more intelligent creator do, especially one that has been around longer, much longer? Perhaps they could create a world so convincing that it seemed constant and even solid to its artificially intelligent inhabitants.

Those inhabitants might even strive to emulate their creators and build crude virtual worlds of their own. The first steps in their building might involve capturing sound energy through physical means and using magnetism and materials such as foil, wire and eventually iron oxide smeared on plastic as a medium for storage. Would the resulting recording of events in that created world be constant if that world itself was not constant, but was just a very convincing sense of constant?

If this were the case, would there be a wireless sync generator somewhere keeping all our senses and stories in step with each other? I'm not paranoid, I'm just wondering.

Digressions aside, digital is certainly different than analog in this sometimes distorted, over-modulated world of ours. A few months ago I replaced the behemoth analog mixing console at my studio with an all-digital one. It took five of us groaning and straining to get the old baby out of the mix room. And it took six 2-foot-square boxes filled with three power supplies, the external computer for fader automation and various cabling to set the board up in its next home.

I carried the new board, a Mackie Digital 8 Bus, into the studio under my arm. The only other hardware that came with it was a PC containing the operating system. It has a built-in Ethernet port for downloading new versions of software over the Internet. The software is the mixer; the buttons on the console merely execute software instructions. And they are multi-functional, so although the board is half the size of my old analog board, it has much more processing and more controls. My analog board had 36 faders; the Mackie has 24, but they work four levels deep, so they do the work it would take 96 faders on my old console to do.

The Mackie also takes advantage of plug-ins from specialized manufacturers of digital signal processing software. These plug-ins are ported within the mixing console with full automation and availability on all tracks. Now mixers will have the same toys on the mix stage that sound editors have in their digital workstations.

The beauty of computer-based mixing boards is that they may never go out of date. Mackie has already responded to user feedback on the D8B regarding some needed additions to the surround panning capabilities. It did not have controls for convergence, which is the ability to regulate the width and depth of the panning. In the new version of the operating system these adjustments are there on the screen for every fader, a done deal.

Another very new all-digital console is the S-5, which premiered at the AES conference in New York in September. The first install of the console anywhere took place at San Francisco-based One Union Recording Studios ,where I am a partner, in July. Manufactured by Euphonix, whose consoles featuring digital control of analog signals are revered by music producers, the S-5 employs digital control of a digital audio path. Earlier Euphonix consoles have been in use in the Bay Area at Russian Hill Recording and Outpost studios for years. The S-5 is Euphonix’s first all digital console. The mixer is basically a pool of digital signal processing, you design the console you need for the session. You determine how many mix channels, how many effects sends, mix stems and other elements you need for that particular session. Just sitting behind it lets you know you’re driving the Aston Martin of audio consoles.

More advantages of the computer-based console:

When you get a setting you like on your console processor, you can store it with the name of your choosing and bring it back whenever you want, for the show you’re currently working on or for any future show. The faders are motorized and, like all of the other buttons, switches and panners are automated by being touch sensitive. Move a knob while time code is running and the move is remembered.

Since all the audio within the mixer is in the digital domain, changing the equalization of a sound or adjusting the dynamics of sounds with compression is done through software. This is much more cost-effective than having to go outside the mixer to a hardware box to carry out the same chore. In addition, every fader provides a choice of types of equalization, a compressor, a gate and a surround panner. The static settings and dynamic changes made to all of these devices are written into the on-board automation and instantly recalled on playback relative to timecode. No out-board processor can do that, even if you could afford the tens of thousands of dollars it would cost to have all those processors on every channel.

Computer-based all digital fully automated consoles are here, check your bank balance and choose your weapon. Don't blink, nothing is constant.

Film/Tape World Magazine, November 1999