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In Reply to: RE: I still haven't heard a satisfactory explanation: posted by carcass93 on December 03, 2014 at 12:39:30
That kind of test is only useful if you have posed the right question and if you understand more about how our sense of hearing works.
Our hearing is NOT like a measurement microphone which is ideally a faithful conversion of the pressure at the mic diaphragm to a proportional voltage. Hearing as we know it is a learned process AND involves not only what we have learned through our lives but also what we see and know. A “blind test” or more correctly I think, a test where you compare two things but don’t know which is which at the time is a way to separate what you see and think from what is entering your ears in terms of sound pressure.
Snipped from;
http://www.audioasylum.com/forums/critics/messages/7/77300.html
Sounds crazy but it's true, in fact our sight can completely over ride what we hear (google and watch the mcgurke effect) and what we know can shape what we hear as well.
So, when you have your hearing tested, they limit the stimulus to one domain, your auditor channels, there is no red light that goes on with the tones, if there was one, your hearing would be much better, the person running the test can't give you any clues, if he winked or you saw him press a button. Your hearing would be much better, even if you weren't consciously aware of seeing it. So in the hearing test, it all depends on what your ears alone can detect.
Just like with wine conisures some hifi enthusiasts have an extraordinarily high opinion of their own capabilities and are very proud (and welcome any suggestion along this line, like a country welcomes an asteroid strike).
In scientific testing methodology, for some things blind testing is the norm however. It is the only or at least best way to minimize bias .
To be scientifically rigorous, one must follow all the rules and protocols and use the appropriate math for analysis. To satisfy the nth degree of precision, is far outside of what is done in hifi. In fact, I am not sure people generally understand there is a connection between what we see, know and expect and what we hear but it is an overriding principal too. We also interpret anything new based on what we already know and understand.
To break the connection between what you know, expect or see and what you actually hear (by hear I mean the air pressure changes entering your ears, all one needs is to arrange a situation where you compare two things without knowing or seeing which was which.
In an informal test like this, do this when you're comfortable with music you have selected at your leisure and usually with a silent friends help (or use a SBX relay box etc), go back and forth between A and B where you don't know which is which. When you find musical snippets where you hear differences and then just go back and forth with those snippets.
Often, people find what they had previously heard as a large difference in sighted comparisons becomes a smaller one, once "the knowledge of which one was which" is removed as then your judgment is only based on what reaches your ears.
Do this A VS B comparison as often as you want, whenever you want until you are sure of your conclusion. The two sound different, the same or a little different.
I think the reason some don't like the idea is because that pretty often, once one has heard the big difference disappear, the magic of it usually doesn't return. The up side for the diy'r is, if you have just made something that does sound better when compared “without knowledge”, it is likely to sound better to most everyone else too even when they also don't know what it is. The up side for the buyer is that one can be “primed” to “hear something special” but if it goes away after a bt, then it was not part of what was reaching your ears but if it was you found something transferable to others.
So, DBT tests are only useful to compare two things and while a great deal of protocol is required to do a valid test scientifically speaking like for a new drug etc, the actual strength of the test in hifi is simply that it forces the listener to depend entirely on their ears and cuts out what you know, see and expect which we are unaware of , is also part of our “hearing process”.
They are much more useful at the engineering stage or for the diy'r as they are more likely to be comparing two things / components etc and rarely would a buyer be able to set up such a test and the marketing agents are generally against comparisons like that.
Follow Ups:
I think you are saying that it's common to stop hearing differences under normal sighted listening conditions after conducting a blind test. But what if you don't? I don't know whether this is typical, but my personal experience has been that differences tend to vanish after repeated A/B comparisons, whether sighted or blind, and then reappear once I'm back to regular casual listening.
Power cables are a good example. As an engineer with a physics background and MSEE, it pisses me off that power cables seem to make a difference on some of the components I've used in my systems. I once conducted a single blind test with the help of my patient wife, and as the test progressed, I got less and less confident of my answers, and the result was null. I also noticed the same effect under sighted conditions: after switching cables back and forth several times over a couple hours, I couldn't hear a consistent difference anymore. But after a few days and and a few casual listening sessions with no changes (to reset my reference point), the differences came right back. I've repeated the comparisons a few times over the years when changing gear. Whenever I think I hear differences between cables, they will vanish during repeated A/B switching under sighted conditions, but they are apparent again in "normal" casual listening over the course of multiple days and several listening sessions.
So what can I do? On one hand, I could forget about power cables and live with a system that doesn't quite give me the same level of satisfaction, and pat myself on the back for sticking to my engineering principles and feel smug that I've 'conquered' the placebo effect. On the other hand, I can continue to mess around with power cords if they make my system sound more satisfying, and live with the fact that I can't prove it to anyone and don't understand why they make a difference. I chose the latter, because even though the difference to me is small, it is meaningful, and I have a preference, and it's something I can't "un-hear" regardless of the accumulating number of failed cable DBTs.
What would you do?
I suggest people buy equipment they like, equipment they prefer. There is no need to follow the results of DBTs (which actually may not narrow down the choices very much!) unless you want to.
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"A fool and his money are soon parted." --- Thomas Tusser
But in this case, I actually wanted to stop hearing a difference!
If you don't know "which is which" but you can hear one is different, then, you have established that the difference you hear IS due to what is entering your ears alone.
Anyway, I was responding to your suggestion that "once one has heard the big difference disappear, the magic of it usually doesn't return".
In my case, I can make the difference disappear under sighted conditions just by switching back and forth several times over a few hours.
But it always seems to come back under regular listening.
So if you're suggesting that taking a blind test can somehow make an audiophile "un-hear" something, that hasn't been my personal experience.
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