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Re: "Objective" audio tests are not objective: An inside view on where objective audiophiles go wrong with their blind t

Posted by tomservo (M) on January 10, 2007 at 08:30:59

In Reply to: "Objective" audio tests are not objective: An inside view on where objective audiophiles go wrong with their blind tests posted by Richard BassNut Greene on January 9, 2007 at 09:39:52:

Hi Richard

Clearly you have accounted for a large number of things, which can make the test non-optimal.
On the other hand, it simply can’t be denied that ones hearing, like all your senses are invisibly tied to what you already think.
This power of thinking is so strong it can cause medical problems to retreat about 1 /3 rd of the time (placebo effect), or even make people sure they can hear the improvement from some little marbles in a jar, little wood blocks or a “quantum” cd fixer sitting on top of the cd player.

So you have the old science question “how can I measure this without perturbing the system under test?” and the resolution / certainty issue, which depends on at one extreme “if” your companies future is at risk on the results or at the other end, if your just curious to find out.

With new drugs its easy (sort of) the people do what ever they did before, every so often they come in and you record the results.
With hifi it is harder because of all the things / ways of doing it you point out that can perturb the system.

Tubeguys proposal is the logical direction to go, set it up at home, do it at your leisure when ever you feel like it.
The actual root point of all the blind testing after all is what counts, to remove prior knowledge of what which one you’re hearing.

Designing and building a switcher (easier for speakers than low level signals) that could pass scientific scrutiny (examination with a network analyzer to assure that electrically, it can’t effect the signal etc) is beyond the hobbyist and until one could be sure that invisibility was reached, the issue of “is the switcher affecting the signal” remains a dark cloud (and for skeptics, would always remain anyway).

The up side for a push button switcher is that it is proven ones acoustic memory is detailed for only seconds and fades with time (references in an earlier post somewhere here).
The up side for actually switching the cables is that the switcher can’t affect the signal and costs no money to do, you just need a helper.

It is important that the levels be adjusted to be the same, it is an old hifi salesman’s trick to raise the level of the speakers they were promoting by 1 dB relative to the others (back in the old days when stores had switchers to audition any amp with any speakers). That small amplitude difference was interpreted as being clearer, not louder.
With electronics it’s easy to do, with speakers it is hard as they have so many different kinds of errors.

Before you test, switching back and forth with knowledge as much as you want, as often as you want and talking about differences is no problem.
If its really important (like if your developing a product etc), leave it set up ready to test when ever you want, when ever your sure you hear something in one, then switch to “without knowledge” test and see if it’s the same, different or gone.
The point is, to set up this “without knowledge” comparison with as little impact on your routine as possible, what that is exactly will vary on the person and setup. To provide insight, you only need to remove the “prior knowledge” which is unavoidably added to what signals our tiny ear hairs detect before us being “aware” of hearing something.

I can’t argue that what you think shouldn’t be part of what you hear, its just that improvements that are only based on what you think (like the little marbles and many other tweaks) are no longer audible when you hear “with and without” but do it without prior knowledge.
In a way, to me, that makes these kinds of products pretty close to being a audio fraud or at least fully illusory like high fashion, Jewelry.
On the other hand, improvements that are heard “blind” are usually heard by other people without prior knowledge as well.

It is cool to see people talking about this, sort of cutting through a perceptual membrane, exploited by many, which all are fully accustomed to or even un-aware of.
Best,

Tom Danley

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