Judging from the reaction to last issue's editorial on double-blind listening tests
— see the posts on the Forum at avguide.com under "Evaluation, Testing, Measurement, and Perception"
— there's no more polarizing topic in audio. Of course, I knew this going in; I've been writing on this subject for nearly 20 years, and didn't expect to change anyone's mind.
Many of the Forum posters believe that the observational listening techniques employed in product reviews introduce human subjectivity into the process of equipment evaluation, thus tainting the conclusions. These individuals believe that the only proper way to characterize the quality of audio equipment is through "objective" measurements (see also the letter from reader Tony Knight in this issue). It is only via these means, by which audio equipment performance is reduced to a series of mathematical representations, that we can discover the truth, free from the biases, foibles, and vagaries inherent in the listening experience.
I've reached the opposite conclusion, not because of any fundamental belief system or because I reject science (in fact, quite the opposite
— most of my pleasure reading is of scientifically oriented books), but because I've spent considerable time in the front lines and have first-hand experience in both worlds. I was hired by Stereophile in 1989 as Technical Editor to set up and run the magazine's test laboratory. Over the subsequent eight years, I measured several hundred audio products, many of which I listened to in my own system. In all that time I can say that I never found a single correlation between how a piece of electronics measured and how it sounded. In fact, if I had to choose a component to live with based on ten minutes in the listening room or ten hours in the test lab, I'd take ten minutes in the listening room.
The reason that measurements don't reflect musical reality is that they are crude, two-dimensional representations of a massively complex system that we don't fully understand. And I'm talking about the equipment itself, never mind the brain's role in converting electrical impulses from the ear into our perception of not only sound but also of musical meaning. It's hubris of the highest order to think that our primitive measurements can quantify how miniscule changes in the electrical signal affect the way the brain experiences music. The value of a change in the sonic presentation depends on the musical relevance of that change. Where do you find that discernment of musical value in THD = 0.02%, channel separation = >110dB, input impedance = 50kohms, and IMD = 0.5%?
As I was reading Nelson Pass' papers and articles recently in preparation for writing the review of the Pass Labs XA100.5 monoblocks in this issue, I came across the most eloquent, thoughtful, and authoritative statement I've seen on the subject.
"There has been a failure in the attempt to use specifications to characterize the subtleties of sonic performance. Amplifiers with similar measurements are not equal, and products with higher power, wider bandwidth, and lower distortion do not necessarily sound better.
"Historically, that amplifier offering the most power, or the lowest IM distortion, or the lowest THD, or the highest slew rate, or the lowest noise, has not become a classic or even been more than a modest success. For a long time there has been faith in the technical community that eventually some objective analysis would reconcile critical listeners' subjective experience with laboratory measurement. Perhaps this will occur, but in the meantime, audiophiles largely reject bench specifications as an indicator of audio quality. This is appropriate.
"Appreciation of audio is a completely subjective human experience. We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines. Measurements can provide a measure of insight, but are no substitute for human judgment.
"Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not.
"As in art, classic audio components are the results of individual efforts and reflect a coherent underlying philosophy. They make a subjective and an objective statement of quality which is meant to be appreciated. It is essential that the circuitry of an audio component reflects a philosophy which addresses the subjective nature of its performance first and foremost."