Audio Etc. by Edward Tatnall Canby (Feb. 1977)

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Socko, one after another, a whole batch of new audio gadgets has hit my ears these past few months. Every last one of them, I note with interest, is somehow intended to increase our active control over the sounds we hear in the home listening space, or the very shape of the sound itself. I've sensed a lot of excitement here, more than usual, and I think the reason is easy to spot. Surround sound plus digital audio. Digital is the spark! It's everywhere, it can do astonishing things, and when the price comes down, which it will, they tell me, once we get away from expensive analog-digital--analog into more direct and cheaper approaches--bucket brigades of them will be mass produced.

Digital plus sound in the round! I talked myself hoarse and wore out my ears at the AES convention last autumn, one of the best ever. We are positively leaping into new things, unimaginable a few years back, ranging I must admit from the sublime to the barely amusing.

Some of these stick to stereo, two good channels and a batch of new tricks.

Some have to do with the other end of the audio chain, new ways to pick up the distributed sounds in the recording space. Some are exploring my favorite long-time hobby, which I knew would have its day-binaural sound in headphones.

(How about phones with ears in them-built-in mikes? JVC has them and I have a pair.) Yet the majority of the new ideas inevitably the straight into surround sound in anywhere from 2- to -16 channels, building upon that fruitful idea which first appeared, so long ago, in early quadraphonic and all its synthesized predecessors, back channels derived from stereo information as in the Dyna loudspeaker circuits which some of us still use. You may think what you like about the present state of commercial quadraphonic, but without the stimulus of surround sound, the very idea of it, not much of the present ferment of activity could exist. There is simply no stopping this new control of our listening space, on all sides, all around, not merely up front.

Digital Osmosis

Aside from digital, new ideas are coming out in sympathy, even in old areas. Take single-point micro-phoning, ancient, from way back, but wow is it back again, if analogish. Two simultaneous developments here from two major organizations, opposite in technology but remarkably similar in intent. One of them is the " Ghent" compound four-way microphone, from CBS Technology Center, the other a pair of binaural-head microphone systems for loudspeaker-intended sound from JVC, and no contradiction, either. There's a version for stereo, and another, closely related, for quadraphonic. Like the Ghent microphone, both of these JVC microphone arrays pick up sound from a single location in the recording space, in the honored fashion of Mercury's Living Presence recordings of years ago, as with a number of later stereo systems, including the M-S (middle side) and crossed mike techniques.

Both CBS and JVC also aim to capture a more accurate and specific wraparound of sound, filling in the side areas where both stereo and quadraphonic reproduction tends to be ill defined.

JVC really grabs those side sounds and reproduces them in both stereo and quadraphonic.

You can hear them, straight out to left and right, many feet from the nearest visible loudspeaker, coming out of nothing. There's spatial control for you.

As for the Ghent, its four microphone transducers, facing the points of the audio compass, deliver an instant SQ encoding in two channels, ready to be decoded into a surround quadraphonic array. Indeed, as I heard for myself, the product is not only a full four-channel sound but does show distinctly improved side rendering.

The JVC system, both stereo and quadraphonic, is an extraordinarily ingenious binaural "simulation"-a computer-developed tailoring of binaural signals, from microphones set in dummy heads, so that the usual overlap of sound heard from pairs of speakers (both ears hearing both speakers) is partially compensated for and eliminated and the ears are actually fooled into thinking the speakers are headphones, more or less. If I am right, it's done by cancellations, rubbing out selectively unwanted phasings. Hard to believe, but the thing actually works. For stereo there is one dummy head, and for quadraphonic a pair of heads, one right behind the other, the rear head's nose jammed into a sound baffle between the two so he hears only what's behind him, and vice versa. A black box arrangement doctors up the resulting binaural signals before they are fed to loudspeakers. And lo! we do indeed get side information as we listen, East and West, and even some more radical directionalities too. I broke the JVC track record: With two stereo speakers in front of me, I distinctly heard a recorded telephone ring behind me.

How's that for control! Get it straight, in case you are confused. Inside head phones, binaural sound is weak in the front and back but very strong at the sides. Speakers are the opposite, both in stereo and quadraphonic, plenty strong in front (and in back) but vague as to side information. So, thought JVC, if you could make speakers sound even a little bit like headphones, you would have your side info. And so you did.

In the Ghent, the four microphone elements are followed by a matrix system which, if I am right, functions virtually as an SQ encoder, right in the microphone assembly, to provide the two-channel SQ output. Considering the size and complexity of the professional SQ encoders I have seen, this is some accomplishment! In any case, there is no doubt about the complete quadraphonic sound array which is the result, all from this single mike unit. Potentially very useful, especially in broadcasting-a single microphone and a signal that can be fed straight into a two-channel stereo transmitter. Lovely for live broadcasts.

Single-Point Limitations

I will have to add that both these microphone systems, JVC and CBS, will have the same problems that traditionally go with any single-point microphone pickup, whether mono, stereo or quadraphonic. Very limited flexibility, if the right balance between ambient and direct sound is to be maintained. Hit the perfect spot, the exact right location, and the sound is gorgeous, as Mercury proved so well. But with the many varied sound sources in modern recording, that ideal spot isn't easy to achieve and because there is a clumsiness in balancing different instruments, near and far, that can only be solved by moving them around, which is the reason we have turned towards the more versatile multi-mike techniques, in spite of their inherent distortions and cancellations.

The first Ghent recording, made live last fall at a concert in England, turned out to be so close that the solo piano in a concerto was overwhelmingly near at hand, drowning out the hall reverb in the final big chord.

Just a matter of trial and error, an unfamiliar microphone and no chance for adjustments during the recording. It should have been farther back.

Yet I felt this was good. It's always easy to pull back a bit, but devilishly hard to move forward without getting into balance problems if your sound is too distant. I'd say the Ghent gives a good liveness ratio of direct to reflected sound, and probably a lot better than a standard omni microphone placed at the same spot.

A curious double effect was observable with the JVC dummy-head system as used in loudspeaker reproduction. First, in spite of those binaurally tailored signals, the perceived liveness appeared to be essentially of the loudspeaker type, and not that of the binaural sound of phones. The recorded voices did come from astonishing directions but they were often "off-mike" and over-live, too distant, as would be the case with normal mikes set up in the one fixed central location. In headphone binaural sound, there is no such thing as "off mike." Sounds are always heard as in nature, at any distance, though perhaps not from the true direction. Not so with loudspeakers and that is why we invented microphone technique in the first place. Move in close, to balance room sound against direct sound.

Binaural Simulation

But there was something else. JVC wasn't giving us regular loudspeaker sound. What I heard from their tailored binaural simulations was as weird as it was unexpected-two spaces, one hovering within the other! There was the normal loudspeaker sound, within the listening room. And at the same time there was another space, a ghost space, pulsing inside the other space; the loudspeakers were trying to create a literal binaural effect, a space independent of the listening room, exactly as in phones. Interesting, but I must say that the phenomenon was unsettling. One space at a time, thank you, and no double exposures.

This was, of course, the direct if unintended result of JVC's success in delivering real binaural sound out of loudspeakers, but I rather suspect that in other types of recording, such as a normal musical job in the usual reverberant surround, the two spaces would blend together and go almost unnoticed.

Still-did you ever see a double-exposed stereo photo, two 3-D pictures interpenetrating each other? That's what I heard.

In a sense, these CBS and JVC one point microphone systems are flying in the face of most current audio development, for we are going more and more into multi-microphone, multi-track, multi-mix-down recording, plus synthetic additions in both sound and space. We are even altering the final sound package, right in the living room. Like Audio Pulse or Sound Concepts. Add-a-concert hall! There is no place for either a Ghent or a JVC mike in one of those synthesized spaces. Even so, it is good to have these new and elegant systems on hand for surround-space recording, if only as useful anchors to windward and a balance against excess, they'll be used.

(Source: Audio magazine, Feb. 1977, )

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