Audio: principles, ground rules

(some thoughts, not a comprehensive study)

Although the audio community seems to be divided into "objectivist" and "subjectivist", this kind of portrayal is too simplistic and misleading. Subjectivism is a faith-based system that comes from a misinterpretation of measurements, sound reproduction or even the scientific method. On the other hand, objectivism is less uniform, some forms are better, some worse.

An audio measurement must be consistent with what we hear. It also has to be consistent indirectly with fidelity. However, measurements are just one side of the story: measurements without models are almost worthless. Measurement without a valid model is just as pointless and wrong as subjective testing without expertise common in subjective magazines, which is responsible for the "blind leading the blind" phenomenon.

So measurements and models cannot be separated from each other, as models are the key to understanding measurements. The question is not how to measure "X", but how to create a model of human hearing, loudspeakers, amplifiers (and even instruments, recording process) and how to build measurements from this knowledge.

In addition to a different attitude to measurements, blind tests are often portrayed as a dividing line between subjectivism and objectivism. However, this is a huge misconception. First, our knowledge doesn't come from blind tests alone. Secondly, understanding technology and hearing is more important than just doing blind tests. Real advances in audio technology come from a deeper understanding of signal behavior, human hearing and real sound sources (from loudspeakers to musical instruments). Understanding the difference between conventional microphone measurements, dummy head measurements and human hearing (two-ear averaging, critical band averaging, precedence effect) is another important subject. Blind tests with music can be used as a secondary, demonstrative tool, but to prove an idea we need to perform an experiment.

Though flawed test methods contribute to the spread of misconceptions, the real source of high-end mythology is always a fundamental misconception related to sound reproduction, audio measurements or even the scientific method. Most of these misconceptions are nothing but a "chicken or the egg" type imaginary problem.

it's pretty obvious that the role of listening tests is misunderstood. Audiophile magazines reject blind testing method based on imaginary reasons. Fake criticism accompanying blind testing is just part of their marketing strategy. On the other side, we are faced with a misconception that all problems have to be solved with blind testing, which led to the most important characteristics being ignored. This characteristics is the sensitivity of tests. The main goal is to design an experiment that doesn't depend on blind testing and use blind listening test with music as a secondary-demonstrative tool. ("If your experiment needs statistics, you ought to have done a better experiment." - Ernest Rutherford)

The most important criterion for an audio measurement is the correlation with perception and fidelity. This requires measuring the "right thing" in the right way and interpreting the results in the right way. How is it possible? If we want to measure the audibility of coloration caused by a component, we need:

This type of categorization should be the most fundamental principle in audio, knowing and using as a compass is essential and mandatory - from nonlinear distortion measurements to cone excursion analysis.

Our auditory memory evolved for communication and surviving, not for testing amplifiers or cables. (Nor have our eyes evolved to test 2k/4k displays...) If we compare hearing and vision then we can see that the ear's analytical ability is much worse than the analytical capability of vision. We can completely separate one part of the image from the rest, but we can't completely separate one part of the music from the rest. Analytical and focusing ability of hearing is very limited. If we also add that humans are visual thinkers, which means that we need a visual representation of a problem to understand the problem, it's no surprise that hifi has become so subjective.

Loudspeaker, headphone "projects"

Although I no longer build loudspeakers and only measure loudspeakers once in a while, I'm still interested in room acoustics and problems related to loudspeaker-room "interaction". Occassionally I measure headphones using the simple flat-plate method (a calibrated electret capsule mounted in a small 15 cm - 17 cm wide box works well). In addition to the flat-plate measurement, I measure the response below 500 Hz with the "capsule in the ear" method.

"So much music, so little time"

Sometimes I'll start a software, and I don't even know where it's going. I just hope I find it along the way. Impro-ware-isaton. Like this YouTube video player with playlist that started last year as a joke and a relaxing hobby.

Csaba Horváth

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