Quibbles and Bits

If No One Ever Reads This Column…

…did I actually write it?

There is a catchy phrase, “Perception is Reality”, which is often thrown about as a pithy epithet, although at times it shows up as a surprisingly profound truth.  The underlying notion is that if you perceive something to be so, then it doesn’t matter what the underlying reality is … only the perception ultimately matters.  The unspoken sneer is that perception is an inadequate proxy for reality, and is polite language for “fooled into believing …”.  However, a scientific approach to the issue can lead to more rigorous and useful definitions of what comprise Perception and Reality.

For example, I perceive my loudspeakers to be standing in the room in front of me.  That’s generally good enough for me to be satisfied that they are actually there.  There ought to be a difference between my perceiving them to be there, and the loudspeakers actually being there.  After all, if I head off to the kitchen where I am no longer able to perceive them, would they in fact no longer be there?  Would they cease to exist as soon as I cease to perceive them?  As a scientist I can provide a number of independent steps I could take to determine whether or not the speakers disappear when I head off somewhere else, and I am confident that those steps will confirm that my speakers do indeed continue to exist when I am no longer perceiving them.  But even so, to this day there are whole branches of philosophy that deal with existential questions such as these.

Even more interesting, there are branches of science which deal with these issues at a profound and elemental level.  Quantum Physics, for example, is very happy to throw at you any number of odd and bizarre experimental observations that appear to be at odds with a rational, conservative view of reality.  And no matter how counter-intuitive these things can appear to the lay person, what we see is that time and time again experimental evidence sides with the weird science against the otherwise “rational” and “logical” positions.  So that, yes, bizarrely enough, there is good science behind the notion that my loudspeakers in reality do not exist until such time as I either perceive them, or perceive the consequences of some other system (or observer) which interacts with (or “perceives”) them.

But a different kind of perception is at play when we come to actually listening to loudspeakers, or more generally to the system as a whole that plays music through them.  The net result is that the system causes the air to vibrate.  Those vibrations impinge on our ears, and our brains set about trying to make sense of those vibrations in the context of the world in which we live.  And that’s very important, because what we perceive is not the vibrations themselves, but rather what our brains are able to make of them.

That may sound like a “pithy epithet” all of its very own, but it is in fact a critically important concept.  Take, for example, a binaural recording played over headphones.  If you clamp your head in a vise you will often find that you can hear a clear and highly detailed three-dimensional sonic image.  But if you free up your head so you can move it – even if only slightly – then the three-dimensional aspect of the image will usually collapse in an instant, and can be frustratingly difficult to re-establish.  In this example, the sound waves being presented to our ears is not being changed one iota.  Only our brains’ interpretation of those sound waves is changing.  It is an extreme example, but it is a good one with which to introduce the general issue here, which is that we hear only what our brains allow us to hear.

I have two audio systems in my home.  One is a no-compromise audiophile stereo setup used for serious music listening.  The other is a 5.1 surround sound Home-Theater system, which is used only for watching video content.  The HT system is massively compromised, and can in no way be described as having audiophile pretensions.  It has four in-ceiling speakers, a center channel of a different brand, and a subwoofer of a third brand.   It is all powered by a cheap mass-market receiver.  The sound is pretty dreadful by any audiophile standards.

Here’s the thing, though.  I have a number of DVDs of live music performances, from opera through rock concerts.  When I am watching the video content I am generally completely unaware of any limitations in the audio quality.  I find I am completely immersed into the performance, and if anything, I would go so far as to say I perceive the audio quality to be rather good.  But if I put a CD in the player instead of a DVD, the result is pretty much unlistenable.  What is going on here?

The answer relates to how the brain works.  And I feel I should point out straight up that for exactly this very reason the specific results I get may not be the same as the equivalent results you’d get.  But that’s fine, because it’s not the specific result that matters here, rather it’s the understanding of the mechanism(s) at play.  When our brains interact with the world at large, they seek to understand what they are seeing and hearing in terms of their experiences.  Our brains have ‘templates’ (for want of a better word) of experiences that they want to try to fit things to.  So, for example, when we see photographs of people in the famous Ames Room, our brains perceive a rectangular room, containing people of unexpected sizes.  But people from primitive cultures, who lived in round rather than square structures, when shown such images perceived an odd-shaped room containing sensibly-sized people.

The Ames Room is a classic example of how we see only what our brains allow us to see, rather than what our intellects would prefer us to see.  I believe my experiences with my Home Theater setup are variations on the exact same phenomenon.

When I play a concert video DVD my brain sees the picture and attempts to match the sound to the image.  Because we are primarily visual creatures, the image, rather than the sound, is the primary point of interpretative reference.  I have a good, clean image on the screen, and so my brain adjusts its interpretation of the sound accordingly.  Not only do I hear a trumpet when I see a trumpet, but I perceive a better-sounding trumpet (perhaps what I really mean is a more satisfactory-sounding trumpet) than I would do if I were not actually seeing clean footage of the trumpet playing on the screen.  When our brain tells us we are seeing a more lifelike image, or hearing a more lifelike sound, what it is really telling us is that what we are seeing and hearing is a more accurate match to its internal ‘template’.

This, to my mind, illustrates a critically important phenomenon, and one I don’t see discussed as widely as I think it should be.  What we have here is clear evidence that how we perceive sound quality can be impacted – sometimes remarkably strongly – by factors unrelated to the actual sound quality itself.  This is something that we, as audiophiles, experience quite strongly, although it generally falls into the category of things we don’t like to admit to.  We tend to argue against the notion that sound quality is something that has to be perceived, because it inherently plays into the hands of those who wish to contend that we never actually hear those things in the first place.  But the fact that a given system can be perceived to sound anywhere from higher to lower quality according to unspecified or unknown factors does not mean that one system cannot sound better than another.  Nor is it inconsistent with an expectation that a better system will have the potential to deliver a better perceived listening experience.

In my mind, the most interesting question is as follows.  Can an improvement in the actual performance of one sonic attribute result in an improved perceived assessment of an otherwise unrelated sonic attribute?  For example, if we improve a system so that it delivers a high-quality three-dimension soundstage (for example, through improvements in speaker placement) can we thereby enable a listener to perceive a more accurate tonal palette?  I have a sneaking suspicion that this might actually be the case [although I do accept that in the simple example given, moving the speakers will affect both the imaging and the tonal balance].  Given that, as I mentioned earlier, humans are primarily ‘visual’ beings, I wonder whether the ability to ‘visualize’ a three-dimensional sound field will help the brain to better fit what it hears to an internal template, such that the listener will perceive a higher quality overall sonic picture?  I know that from my own personal experience, my overall listening pleasure is maximally enhanced when I perceive good, holographic imaging, although it is not clear to me whether under these conditions I also perceive a specific improvement in, say, tonal accuracy.  In any case, I must emphasize, this is pure speculation on my part.

But the other side of the coin is when people try to perform the dreaded “double blind test”, the bane of the audiophile world.  Because the factors governing perception of sound are still very much unknown, we do not yet have a scientific basis upon which to establish test conditions where what the subjects perceive is sufficiently well controlled.  It is not surprising, therefore, that the results of such tests are seldom satisfactory to the audiophile community, whereas the community of skeptics can continue to wave the perception issue in our faces and snort that we are all just fooling ourselves.