Reviews with all double blind testing?


In the July, 2005 issue of Stereophile, John Atkinson discusses his debate with Arnold Krueger, who Atkinson suggest fundamentally wants only double blind testing of all products in the name of science. Atkinson goes on to discuss his early advocacy of such methodology and his realization that the conclusion that all amps sound the same, as the result of such testing, proved incorrect in the long run. Atkinson’s double blind test involved listening to three amps, so it apparently was not the typical different or the same comparison advocated by those advocating blind testing.

I have been party to three blind testings and several “shootouts,” which were not blind tests and thus resulted in each component having advocates as everyone knew which was playing. None of these ever resulted in a consensus. Two of the three db tests were same or different comparisons. Neither of these resulted in a conclusion that people could consistently hear a difference. One was a comparison of about six preamps. Here there was a substantial consensus that the Bozak preamp surpassed more expensive preamps with many designers of those preamps involved in the listening. In both cases there were individuals that were at odds with the overall conclusion, and in no case were those involved a random sample. In all cases there were no more than 25 people involved.

I have never heard of an instance where “same versus different” methodology ever concluded that there was a difference, but apparently comparisons of multiple amps and preamps, etc. can result in one being generally preferred. I suspect, however, that those advocating db, mean only “same versus different” methodology. Do the advocates of db really expect that the outcome will always be that people can hear no difference? If so, is it the conclusion that underlies their advocacy rather than the supposedly scientific basis for db? Some advocates claim that were there a db test that found people capable of hearing a difference that they would no longer be critical, but is this sincere?

Atkinson puts it in terms of the double blind test advocates want to be right rather than happy, while their opponents would rather be happy than right.

Tests of statistical significance also get involved here as some people can hear a difference, but if they are insufficient in number to achieve statistical significance, then proponents say we must accept the null hypothesis that there is no audible difference. This is all invalid as the samples are never random samples and seldom, if ever, of a substantial size. Since the tests only apply to random samples and statistical significance is greatly enhanced with large samples, nothing in the typical db test works to yield the result that people can hear a difference. This would suggest that the conclusion and not the methodology or a commitment to “science” is the real purpose.

Without db testing, the advocates suggest those who hear a difference are deluding themselves, the placebo effect. But were we to use db but other than the same/different technique and people consistently choose the same component, would we not conclude that they are not delusional? This would test another hypothesis that some can hear better.

I am probably like most subjectivists, as I really do not care what the outcomes of db testing might be. I buy components that I can afford and that satisfy my ears as realistic. Certainly some products satisfy the ears of more people, and sometimes these are not the positively reviewed or heavily advertised products. Again it strikes me, at least, that this should not happen in the world that the objectivists see. They see the world as full of greedy charlatans who use advertising to sell expensive items which are no better than much cheaper ones.

Since my occupation is as a professor and scientist, some among the advocates of double blind might question my commitment to science. My experience with same/different double blind experiments suggest to me a flawed methodology. A double blind multiple component design, especially with a hypothesis that some people are better able to hear a difference, would be more pleasing to me, but even here, I do not think anyone would buy on the basis of such experiments.

To use Atkinson’s phrase, I am generally happy and don’t care if the objectivists think I am right. I suspect they have to have all of us say they are right before they can be happy. Well tough luck, guys. I cannot imagine anything more boring than consistent findings of no difference among wires and components, when I know that to be untrue. Oh, and I have ordered additional Intelligent Chips. My, I am a delusional fool!
tbg

Showing 5 responses by gregm

Tvad sez:
I said I don't believe I can reproduce the live event. Indeed, this is what I believe
Of course you can't. You can only reproduce what the recording process produced and stored on the medium used...

Add to that, the imperfections & losses due to the recording process, the imperfections & losses due to the storage medium and the imperfections & losses due to the reproduction system.

In all of our rantings, we are addressing the last of these (the repro system)

At its best, a reproduction system aims at coming close to the original, i.e. what's on the RECORDED medium (not the live event); this seems to me a reasonable target for us audiophiles.

For the live event, you go to the concert hall.
ELdartford sez
the ear senses RATE-of-change of pressure (...)Have you heard any other explanation
Well, 1) about 20yrs ago a french prof (forgot the name) claimed findings that the bones contribute to our perception of very high frequencies. 2) There seems to be a case for the interaural mechanism working together -- not ONE ear alone, but both being excited.

OTOH, it's also been established that the audibility of PURE tones diminishes with age in the higher frequencies. So here, we're talking about "sound in context": i.e. say, harmonics of an instrument -- where the fundamental & certain harmonics are well within our pure tone hearing range and some of the related info is outside an individual's "official" (pure tone) audible range.

The strange thing is that our ears work as a low pass; so, some people speculate that it's the COMMON interaural excitation that does the trick...
For this to happen (let's ignore the possible contribution of the bone structure for now) would'nt it mean that our interaural "mechanism" is situated in the DIRECT path (sweet spot) of those frequencies (remember, our acuity falls dramatically, ~20-30db, up there). If so, then moving our head slightly would eliminate this perception.

So, let's assume a super high frequency transducer with excellent dispersion characteristics and thereby eliminate the need for that narrow sweet spot (a Murata is quite good, btw).

It is my contention (but I have no concrete evidence) that three things are happening in conjunction:
a) the high frequency sound is loud enough to overcome our reduced acuity up high (at -60db perception our ear would basically reject it)
b) the sounds in our "official" audible frequency range are rendered more palpable (for wont of a better word) because the super transducer's distortion points (upper resonance) have moved very far away (it's ~100kHz for a Murata) -- hence "perception" of positive effects. This still relates to our "official" range of hearing.

b) there is a combined excitation of aural and other, structural, mechanisms that indicate the presence of high frequencies -- that we cannot, however, qualify or explain (our hearing is a defense and guidance mechanism geared towards perceiving and locating).
Even at B there is a dilemma: in a small experiment in France some subjects were asked to put one ear close to a super tweet and declare whether they perceive anything. Inconclusive (some did, some didn't, no pattern. BTW, I did a similar thing & did perceive energy or lack of it with some DELAY however when the tweet STOPPED producing sound -- joining Eldartford's idea).
Subjects were then asked to move away from the transducer & listen normally (stereo), just by casually sitting on a couch in front of the speakers as one would do at home. Everyone "heard" the supertweet playing. Amazingly, only the s-tweet was connected (at 16kHz -- very high up for sound out of other context).
I find this fascinating.
DBT assumes that we have to justify our purchases to others as in science; we do not have to do so
Actually that's an interesting take.
Yet, there's a lot of emotion and correspondingly little logic in the vehement assertions contained in many posts.
Amazing, isn't it. We WANT others to bless our choices after all -- AND, if it's an EE (i.e. scientist) so much the better: science is irrefutable:)
Pabelson, thanks for yr kind words, but the quotes you make refer to another poster -- or are they there to illustrate yr previous points?

Qualia sez:
other things being equal, a beautiful soprano actually *sounds* better in the typical soprano role
Good point! Matter of fact, I read s/where that a nice-looking piece of equip was invariably "heard" to sound "better" than itself unsighted. Amazing!
the illusion is the false reality. Kinda by definition
That is correct, semantically. It's also kinda philosophical.
IMO we should distinguish between semantics and philosophical extrapolations and the simple PRACTICAL application of DBT in our (restricted) context.

BTW, I also suggest that certains things CAN be indicative of performance or INFLUENCE things, in OUR context, such as:
*measurements -- as long as we measure what correlates to what we're looking for (i.e. we would have to determine in advance which measurement indicates what aspect, in terms of perceived sound; little has been done there)
* wires for example -- because they link two electrical circuits, active / passive & combinations thereof
* active components: their circuit design, power supplies, input & output stages, components used... influence the distortion levels AND how well these components interact with the load. Change the load (what the output stage "sees") and things change electrically; if we change something in the system, we've modified the system "circuit" fer pete's sake. Things may also change in the audible range...

...etc.

So, maybe we are discussing whether it's worth setting up dbt to help notice differences in the audible spectrum?
Or whether perhaps dbt is not the most efficient/reliable method of doing so in this particular context?
Or, perhaps, discussion is a way of communicating -- a marvellous, human activity that we all need. And the subject of dbt allows us to do just that -- so what we really want to do is to talk regardless and dbt offers us just that opportunity, whether it is or isn't panacea.
I go for the latter -- my take of course! Cheers:)