Over, Under, Sideways, Down - EMusician

Over, Under, Sideways, Down

A new system puts you in the middle of the audio action.First, commercially recorded sound was monaural. Then, it was stereo and - briefly - quad. Now,
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A new system puts you in the middle of the audio action.

First, commercially recorded sound was monaural. Then, it was stereo and - briefly - quad. Now, it often employs six channels (five full-range and one low-frequency, which is known as 5.1 surround sound), seven channels (6.1), and more. Is this trend likely to continue? Probably; after all, more is always better, right? Well, maybe not always, but this is certainly true when it comes to a sound system's ability to reproduce the directional cues that occur in a real-world acoustical environment.

This is the idea behind the patented Taylor Array Processing System (TAPS) from Dimension Audio (www.dimensionaudio .com). At the recent AES Convention in Los Angeles, the company demonstrated a 45.3-channel version of the system (45 full-range and 3 low-frequency channels). This megasystem included 45 Genelec 1029A powered monitors: eight on the front wall, ten on the right and left walls, seven on the back wall, and ten on the ceiling. Two of the three low-frequency channels were directed to four Buttkicker tactile transducers connected to a floating floor, and the third bass channel was served by a Genelec powered sub.

The system is intended to reproduce sound with as much spatially correct cueing as possible to create a completely enveloping sonic environment. Each full-range speaker is called a sound pixel; much like video pixels combine to form a complete visual image, the sound pixels combine to form a complete aural image. The entire array forms a singular surface - a sort of "meta" speaker. This surface radiates sound in a manner similar to real-world sound waves, combining both near- and far-field cues.

The source material for the AES demo included several selections that had been mixed to 48 discrete channels in the company's studio and played back from two synchronized Soundscape R.Ed 24-track hard disk recorders. Also included were several cuts from standard stereo CDs and 5.1-channel soundtracks processed through the company's patented Sound Spreader software running on a Windows PC and using the two R.Eds as output devices. (The software can also be used with six Soundscape Mixtreme sound cards, each of which provides eight audio outputs.)

Sound Spreader, which has been under development in various forms since 1996, is currently in an alpha version that uses Soundscape hardware. It accepts any signal and uses proprietary DSP algorithms to distribute the sonic energy throughout the array, enlarging the aural image in a relatively fixed, predetermined way. Another program, Pather, can redirect the source signal to any set of output channels based on various criteria.

Even more ambitious is Dimension Audio's plan to introduce a computer-aided design system called AudioCAD that will allow engineers to design multichannel sound environments visually. With this system, a sound designer specifies an ambient environment (a reverberant alleyway, for example) and places sounds at any location within that environment. These sounds can then dynamically "pan" anywhere within the speaker array with the same energy signature as if the sound was actually originating in the specified environment.

Ultimately, a TAPS system can be constructed with any number of channels, but 16 seems to be the minimum number needed to create a convincing sonic environment. Within such an environment, each speaker level (and thus, the required amplifier power) can be relatively low while the overall system maintains a high total SPL. In addition, there is no "sweet spot"; all listening positions have their own complete perspectives of the mix. Appropriate venues include commercial cinemas, dance clubs, video-game parlors, and high-end home theaters. In the studio, Sound Spreader can be used to expand conventional mixes, allowing the engineer to examine the mix, revealing flaws that might otherwise have gone unnoticed. This fascinating technology could have a major impact on all aspects of sound recording in the future.