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  1. In your example, if the "true" voltage difference between points A and B in the circuit is highly variable over time and can actually reverse, then even with highly accurate and reliable voltmeters you will not be able to determine whether there is an ongoing difference in voltage, unless you can move the test prods very quickly (faster than the voltage difference is changing); or, of course, can measure both points in the circuit simultaneously. However if there is a persistent, ongoing, difference in voltage (of the same polarity) you should be able to ascertain whether or not
  2. Although I don't tend to follow commentary on MQA all that much, I can remember seeing the first 3 of those points being presented in the past. Also I have often seen mentioned that the blue light merely shows that a recording has been put through MQA processing, not that it is inherently high resolution or of outstanding high quality. To my mind, where the video in the opening post really shines is in its presentation of objective testing of real life MQA performance. It persuasively and credibly shows that the practical application of MQA can lead to some quite poor outcomes.
  3. No, that's an unduly restrictive definition. Double blind simply means that neither the subject nor anyone interacting with the subject knows whether the variable is present or absent. There is no requirement that the nature of the variable be kept secret. A classic case is a double blind medical trial. People in some parts of the world (e.g. the USA) have volunteered to be guinea pigs for certain covid-19 trial vaccines. They were told they would either be injected with a trial covid vaccine or a placebo. Of course they were not told which! They were "blind" in that regard. And th
  4. There's no need to embark on a fully-fledged DBT exercise for those types of matters, not in the first instance at least, I'd suggest. The sort of approach in my example above of Charlie and Dave doing a brief preliminary informal test of a premium DAC would help in discovering whether someone appears to be able to hear a difference under blind conditions. People typically fall by the wayside even with a brief preliminary test, and typically feel quite surprised that the difference they clearly heard before is now difficult, or actually impossible, to hear. You can avoid a lot of
  5. You identified some deficiencies in DBT technique, and some exaggerations or errors in conclusions drawn. I don't think posters in this thread have disagreed with your "assessment" that there were indeed deficiencies in technique and that there was indeed overreach in at least some of the conclusions reportedly drawn. Where I think opinions differ in this thread is in the level of earnestness in believing that the reason for failure to pass a DBT in the tests your reviewed was probably not a lack of hearing ability, but most likely entirely attributable to flaws in the testing pro
  6. Traditionally, actors have played the Doctor Who character with an urbane educated accent, and a touch of eccentricity. A notable exception was Christopher Eccleston who played the 9th Doctor for a very short period of time. He employed a thick regional accent, and presented as a very down-to-earth character indeed. David Tennant's 10th Doctor was down to earth but still with an urbane manner. He didn't use his own natural Scottish accent but a modern educated Thames estuary style of speech (with a hint of cockney from time to time). Peter Capaldi used a Scottish accent but again it had an an
  7. Tests typically involve pressure. Some people thrive under it. Some wilt. Some are not affected at all. For instance, assume an audio DBT of a group of 10 test subjects results in sufficient stress that the hearing ability of two of the participants is significantly impaired, whereas the hearing ability of the other 8 participants is not. I don't think it would be fair or appropriate to describe such an exercise as "completely flawed". School students sit for tests quite regularly and some students perform less well because of the stress they feel to perform. People go f
  8. I think Grant's dot point above could usefully be expanded upon. Although sighted listening to barely audible stimuli carries little (if any) weight in a formal context, it can I suggest be useful as a starting point in certain informal contexts. I would suggest that for audiophiles at home, sighted listening will typically be a convenient starting point for them to identify something that appears to them to make an audible difference (e.g. a "tweak" of some kind to their system). If with sighted listening, such a difference appears to be present, then to verify that, a blind
  9. I was considering mainstream cases where there is a difference in the audio that is apparent enough for at least some people to hear it unsighted. My suggestion was that in that situation the challenge of listening out for the difference in a formal DBT test could very possibly increase the likelihood of the difference being heard by a person (rather than decrease it because of "performance anxiety"). This would because the person might normally be so interested in listening to and appreciating the music that minor changes in the performance of the reproduction technology could easily pass u
  10. 1. If one ceases to be able to hear a difference because one is "under pressure to perform" that suggests that the perceptual difference is small to begin with. In other words, one's ability to hear the difference is only marginal. In these circumstances it is arguable that one's ability to hear the difference is so tenuous that the difference made by the change (whatever it happens to be) is not worth worrying about! For practical purposes, the perceptual difference is so small as to be negligible. 2. One can make a converse argument, that only when put under pressure to perform
  11. I guess it depends on what you mean by "statistically similar". Your original statement I responded to was: "The most important test for any experiment is that it is consistently repeatable. I've not seen a lot in the literature that suggests that research around audibility includes publications showing repeated results. In fact I see that particular fault in a lot of research areas these days when I go looking. But nobody can claim scientific consensus without it." I note that normally it is enough to find a correlation in a study, let us call it test "A", to a recognised sign
  12. I'd have thought that for audiophile purposes averages for a group would be less important to establish than the performance of high listening acuity individuals. What use would a statistically "average" measure be put to? For example it were found that the upper frequency hearing acuity for a population of adults had a mean value of 14kHz, would it be wise to use that value figure for the design and testing of microphones and loudspeakers? Certainly not. Years ago I was frustrated with a car radio gain control that provided gain changes in minimum steps of 1dB. I prefer to be a
  13. I don't think one should expect repeatability of results in a test of an individual's ability to discern an audible difference if the difference presented to the individual is in that grey area of perception where a stimulus is only barely audible to the individual. For example, if the difference under investigation is the audibility of a difference in signal level of a short segment of music, one might get DBT results as follows: % correct DBT answers over 20 trials | Difference in signal level presented to the listener 100% 4.0dB 100% 2.0dB
  14. Yes that would provide an interesting set of comparisons. _______ (Although motherboard sound can provide 5.1 or more analogue output channels, I think in my testing I'd limit myself to Front Left and Front Right.)
  15. That may be your experience, rmpfyf. It isn't mine. If I find the time in coming weeks I might record the output of one of my pc's with its onboard sound and upload it (level-matched) and the source digital file, let's say with both at a 48kHz sample rate (a very common rate these days). I'd then invite forum members to express their opinions as to the extent of audible differences, e.g. "extreme", "stark", "mild", "barely noticeable". That could be an interesting exercise.
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