It is no accident that man perceives the 'reality' of this world through his senses, or rather through the manner in which it is interpreted by his senses. Prime among the senses are vision and hearing. No doubt, the requirements of evolutionary survival and mastery of his environment subsequently have fine-honed these sensory faculties and endowed them with capabilities that at times defy fuller comprehension, or at any rate invite our wonder and disbelief.
The visual system --the eyes and the brain-- is a devilishly fast and accurate 3-D signal processor that has the added merits of a built-in peripheral vision sub-system that is tuned to simultaneously sense even the faintest of movements in the lowest of light. No system man has devised has approached the complexity and perfection of our visual system. Period.
It is not difficult to surmise that the sense of hearing too is likely to have evolved to a fine degree of complexity and sophistication (so far as input signal processing and interpretation is concerned) once we could see that hearing has been more than a capable partner to vision in ensuring the evolutionary march forward of man in a difficult and dangerous environment. I have commented on the basic aspects of the topic in my earlier posts here. The acuity and accuracy of the ear-brain combo, an accepted fact that has very many proofs in everyday situations even at the present time when man's survival has come to depend less and less on his senses, have also been demonstrated by many researchers in the field.
While considering the aspect of 'reproduced reality' as an exercise in the re-creation of the original scene in both its visual and auditory aspects brings up another interesting side-comment. Ever since the first day of the demonstration of moving pictures, man has been dreaming of 'canning' events that pass into the oblivion of the past. Over the past decades, success in that attempt has taken huge strides forward. Perhaps one of the most immersive of such 'realistic' experiences is the IMAX movie system. We have at present a plethora of systems that claim to reproduce 3-D visual reality and a truly immersive visual experience. But the question is, do we really take that re-creation of reality as the real thing itself? Or, in other words, are the eyes truly and fully 'deceived' into accepting it as reality? Hardly. I am not forgetting the degree of realism that is provided by many audio-visual simulation system powered by heaps of computing power. But the honest answer is, though they come close, sometimes wonderfully close, to the 'real thing', nothing like a full-scale 'deception' is staged. That being the state of affairs, won't it be prudent to aim for and accept a similar situation in the auditory field too ?
Raising the 'Fi'
Ever since the invention of that tinfoil contraption that wheezed out a passable imitation of "Mary had a little lamb...", man has been trying his best to 'can' acoustic events with all its aspects of reality intact. To the contemporaries of Edison, his phonograph was 'life-like' and that was a sure-fire jaw-dropper. It is interesting to watch how every development, every bit of improvement was hailed as another notch up in 'fidelity'. In the electrical/electronic era, the definitive term was 'hi-fi', which has stuck with us till the present and it looks like it is not going away anytime soon. However, the 'height' 'fidelity' has achieved till date is somewhat questionable, though its aims were honourable!
Fidelity is a simple word that could mean "..the exactness of the copy to the original..", and in the case of the re-creation of an acoustic event, the triggering of the feeling/s that one is at the original venue. One moment you are in your living room, and the next, perhaps in the front row of a concert hall... or in the immersive rhythmic din of the live rock concert ... or in the intimate company of jazz musicians in a club ... you ARE there!
Over the ten decades that made up the last century, it was one thing or the other which the audio questor energetically hunted after in his search for 'nirvana' in audio --a 'full' frequency response that surpassed the limits of audibility, the absence of noise and distortions of all shades and types, virtually unlimited power on tap, and along with that tremendous slew rates in amplifier specs, a whole lot of 'classes' of amplification, vacuum tubes, bipolar transistors, MOSFETs and other exotica...a mind-boggling variety of speaker designs ... each with its promise of the Holy Grail of a perfectly realistic reproduction. The 20th C saw wonderful advances in Digital Signal Processing and it seemed the possibilities now were truly endless, and everybody thought digital was going to be what finally delivered the elusive Grail to man thirsting for true fidelity in reproduction.
The task of recording and reproducing the simplest of acoustic events with a virtually foolproof "deception coefficient" has, however, eluded the technical wizards of our era. Period. I am not forgetting the astonishing level of verisimilitude that some systems have been able to project, but one has to be reminded that there were a lot of 'conditions' for that to happen. To achieve even a modicum of 'reality' with possibly the 'best' conventional stereo reproduction system, you had to sit in the 'sweet spot', rigid as a dummy, with hair parted in the middle... and even then, wonder of all wonders, NOTHING that you could throw at it really deceived the ears to any degree, except trigger occasional bouts of fleeting illusion at best.
The Natural Way
The jury is still out on the debate whether it is good or bad that Henry Ford did not imitate Nature, or its corollary, if it was good or bad Nature did not imitate Henry Ford. So far as we know, Mr Ford is the papa of assembly-line mass production. It is educative to think why Nature, with her requirements of producing the millions of clones of just two different models, did not opt for a convenient and efficient conveyor belt system. We then would have had no duds or non-conformists in this world! Sadly that was not how She chose to work, and therein lies a clue to her methods.
A little 'side-step' at this moment brings us to some interesting questions, and not many answers. Man, with his logical and scientific mind, launches into 'production' of what s/he wishes to make once the prototype has been perfected, and the tolerances set. Quite the thing to do if you want to have predictable results and repeatability. Or so we think. I had occasion to be with two friends as they signed on the dotted lines and became the proud owners of the same model of cars with near enough chassis numbers. Naturally they were 'identical' copies in every conceivable way. But sadly, they 'drove' differently. Ditto experience with another set of audiophile acquaintances. The guy had just one listen to an amp-speaker combination at his friend's place, and fell in love with the 'sweetness' of the system, (True, something more or less similar happens in the case of falling in love/getting married too! ...why do they call it "falling" in love...??? ) and promptly ordered an 'identical' set from the dealer. But then big disappointment upon audition at home. He then carted the whole system to the friend's place for a side-by-side comparison with the 'original', and discovered that though the situation was a lot better, still '"something was missing". In the case of amplifiers and speakers, such behaviour brought on by manufacturing 'spreads', though still within 'tolerance', is not totally unknown to many.
That perhaps ought to remind us that aren't we lucky that Nature (and/or God...) chose to eschew the assembly line concept and instead opted for the more fuzzy methodology. Had she gone the way of Papa Ford and most others in 'assembly-line production', we would have ultimately ended up with millions of 'models' with wide tolerances in hearing, but still "within specs" when it came to (let us keep things simple, and for the moment forget about the other faculties) hearing accuracy. The result would be some of us out on a hunt won't be home for that late evening session around the campfire, thanks chiefly to our 'spec-accurate' ears had told us that a faint threatening growl was coming not from right behind you, but from somewhere far behind and off to one side... and again, the chorus of the crickets was particularly loud that evening!!
The auditory system, though it has come into much disuse as a result of man's metro-morphosis these days, has a record of astounding accuracy in imaging. These faculties were no doubt developed and fine-honed over the millennia of evolution and survival. A corpus of scientific research work exists that has tried to study and understand the finer aspects of hearing. It is easy enough to come to the conclusion that there are primarily three overlapping mechanisms of hearing that contribute to accuracy of imaging and 'realism'. The first, applicable over the low octaves, relies on Inter-aural Time/phase Differences (ITD) to clue the brain as regards the direction of sources of sound. In the next few octaves at the low-to-mid level, the Inter-aural Level/intensity Differences (ILD) rule the roost. But when you get into the higher octaves above the mid frequencies, a complex 'filtering' done by the external ear or pinna, interprets the directional clues to the max. Our interest in stereophony has resulted in voluminous studies as regards ITD and ILD. But despite many revealing studies, the pinna and its supreme contribution to the mechanism of hearing seems to be largely not given the attention it surely merits.
The evolutionary needs of hearing/directional accuracy has resulted in a unique 'natural' approach to the mechanism of directional analysis. This aspect assumes extraordinary importance when you consider the fact that there is no 'standard' human being, or for that matter, no 'standard' ear too. For a complex living being that assumes its ultimate shape and functionality after a mind-boggling set of millions and millions of cell divisions after the seminal fusion of just a couple of cells, it is not surprising that the human system is not a 'Xerox-copy' of a master blueprint. Rather, it is a highly unique and individualistic system built according to some master specs. As we all know, the fingers and eyes of the human being carry unique individual patterns (http://en.wikipedia.org/wiki/Fingerprint). Nobody has found an identical set of fingerprints from two different humans--yet. And again, the unique retinal patterns (http://en.wikipedia.org/wiki/Retinal_scan) are accepted as identifying markers. When it comes to the ear, the individual ridges and convolutions, the size and shape, the channels and protruberances of the external ear, or the pinna again, have no 'equals'. It would be interesting to take photographs of your own left and right pinnae and study them side-by-side, and be astounded to discover subtle differences--they are NOT cast in 'standard' moulds. Yet, in spite of these marked and 'serious' variations, the individual's sense of aural accuracy remains astoundingly 'standard'.
The Secret of Hearing
Looking into the 'secret' of hearing accuracy leads one to certain conclusions. Nature in its infinite wisdom has, instead of relying on 'standardized' solutions, has taken recourse to the ploy of embedding these individual 'filter characteristics' within the brain after a long period of 'training'. No doubt the shape and patterns of the external ear or pinna changes subtly over the years as the individual grows up. But one "wears the same set of ears" from one's birth till the end of the journey, and as we live within an ocean of auditory events, it would be an easy matter for 'training' the ear/brain combo, with visual verification/confirmation of the direction and distance of sound clues. In a short while the individual masters the complex filtering of his pinnae, and as a result, is able to interpret the directional clues based on the 'pinna transforms'.
Studies conducted about the nature of pinna transforms (Moller, Hofman, Van Opstal and others) and its abilty to accurately interpret front/back, up/down etc clues have confirmed these observations. Modification of the pinna's physical contours and repeating the studies have confirmed that the ear/brain combo is able to 're-learn and adapt' to the new/modified filter characteristics after a short while, and as a result, the ability of the volunteer subjects to accurately interpret directional clues, which had plummetted initially post-modification, came back to 'normal' levels.
The Individual Pinna Signature
However, the one aspect as regards pinna transforms that has not yet got established in current theory and practice is that the pinna IS the "decisive factor" in hearing and our perception of realism, however you might define that. This is particularly so when considering the recording and reproduction of acoustic events. It is common knowledge that a surface understanding of the functions of the pinna has launched investigations into ways of "tricking" the ears into believing that "you are there" at the original venue of the recorded acoustic event. These technical legerdemains have to a great extent been successful also, though to differing degrees. But whatever "sleight of hand" one might do, it remains a fact that the ears will ALWAYS detect that a reproduction is not the real thing, unless and until you factor in the pinna and its individulized filtering into the final equation. This is so because the brain looks for the individual's own 'pinna signature' in the signal/s being fed in and analysed, and when it cannot detect any trace of that, it concludes that the signals being heard are not "heard properly", and as a result they are NOT real!
The 'Atma of Hearing'
The ability of the ear/brain to detect vague 'copies' as not being originals is a foolproof method. However, while researching ways to re-create reality, we often ignore the absolutely unique and individual nature of the pinna transforms and its key position in the hearing mechanism, which can only lead us astray. This is where I would like to introduce what I call the 'Atma of Hearing' concept. My contention is that only when we succeed in "splicing in" the individual 'atma of hearing' signature into a recorded event, will our ear/brain accept as 'real' a reproduced acoustic event, because then only will we appear to be "hearing" that acoustic event " with our own pinnae" and not with "another's ears".
The Indian Vedic philosophy proclaims 'Ayam Atma Brahma' --"This soul is God".The Atma (the soul) or Atman, which is but a miniscule fraction of God's Divine Spirit, is central to the individual existence. And it is UNIQUE. Atma also means the 'essence', here the essence of human individuality. One is able to understand the concept when one considers the jaw-dropping complexity of the human body and its systems, and also reminds oneself of the fact that without the 'essence' or 'atma', it is nothing but a collection of dead, lifeless tissue.
In the mechanism of hearing also, the "soul of hearing" is nothing but the individual pinna transforms, without which everything loses its 'natural' purity and realism. Like the individual soul, the 'atma' of hearing too is an absolutely unique 'essence' that 'lives' within the brain of the individual as a result of the life-long integration of that signature into everything that the individual hears. Anything that bypasses this "signature filter" is interpreted as being not REAL.
So perhaps it is time we re-channelled our largely misdirected energies questing after the various artefacts of hearing like frequency response, distorion elements, and such like stuff (not that they are worthless; but rather, they do not form the core, and so merit only secondary attention) into a whole new avenue, that could in all likelihood lead us nearer to the Holy Grail of hearing. Our efforts will be crowned with success if we are ready to accept the fact that within each individual there reposes a unique 'Atma of hearing', and the integration of that into the chain of reproduction holds the key to the re-creation of reality from an auditory perspective.
More than ever, the concept is perhaps closer to realization in the digital age as we now have advanced tools like DSP that in all likelihood will be able to reward our efforts to "measure and codify" the individual 'atma' signature and "splice that in real time" into the digital data that represents the three dimensional sound field captured at the original venue. This then will be the one sure way to transport the listener 'there', as s/he will be once again "hearing it all with her/his own beloved pinnae".
How to achieve that should occupy us in the days to come if we are serious about 'reproduced reality'.
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