These are not my words, (in fact I hope that the gentleman who wrote it will understand my intentions for posting it here.)
Charlie
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Double blind tests need to be organized in a way that is stress reducing, not stress building. Listeners need to have free, sighted PRE-testing of the devices under test with the program material that will be used. They need to have as much time as needed to listen for differences and characterize them so that any difference they believe they are hearing they can be familiar enough with it to recognize it during the double blind experiment. At any time during the double blind experiment they should have the freedom to go back to a sighted casual mode to RE-learn any difference they may feel that are having a hard time identifying during double blind. Also, at times it is good to set up a double blind test that can include extended listening with each device, even days if desired, to more closely simulate the listeners normal approach to evaluating equipment.
Double blind does not have to be a rushed, rigid session that takes all the control away from he listener. I feel the listener should be given all the control possible, short of knowing what device is playing at any given time.
When you do the experiments this way, what you find is that for any REAL differences you can actually detect them easier in the controlled testing than you can with casual sighted testing. I've shown this many times in the past by introducing just noticeable distortion levels and asking listeners to try to notice the change. Most listeners find it very hard to hear a real, just above threshold difference when it is introduced in their system without controls and careful level matched, blind switching. When we go to the controlled method they can identify differences quite easily.
This doesn't seem to sink in with the subjectivists that plug in a new component and immediately wax rhapsodic about the amazing changes they hear.
I try not to get people involved in double-blind "challenges" because those often create a stressful situation that serves no one. They need to be set up as a quest for answers rather than a challenge. That is why it is often much better to train listeners who have no particular stand on the situation rather than use seasoned audiophiles with preconceived notions.
I tend to avoid using double blind tests for vengeful purposes...except when unduly provoked.
It turns out that most uncorrelated differences (ones attributed to, but not related to, different devices under test) are most often heard due to one of four things:
1) Level mismatch
2) Lack of controls relative to listener position, head position or room acoustics constants. Even listening by your self vs. having a friend on each side of you creates a dramatically different acoustic which changes amplitude
responses to levels above audible thresholds.
3) Inherent poor audio memory that us humans have (much worse than most audiophiles know or are willing to admit).
4) Including and related to 3 and most often the culprit: We don't usually compare with a short repeat loop of program material and most instruments actually sound slightly different throughout a song depending on which moment of the song we are comparing to another moment. Music itself is inherently a very poor test signal, from a control standpoint. Most differences can actually be heard much easier with nonmusical test signals but I don't know many audiophiles that want to accept that notion either.
These are the things affecting real perceived differences but not related to the equipment. These don't even include the dreaded imaginary differences due to beliefs about particular equipment or a predetermined attitude that there will be some kind of difference between any two DUTs.
Lot's of room for error folks. Everyone, whether subjectivists or not must not think they are somehow exempt from these illusion creating variables. If you control all of these things you will find that your non blind listening will take on a lot more reality. Double blind can become less necessary to those who use proper care in their controls.
Either use the controls to have more assurance of uncovering reality or don't and just have fun enjoying your system.
Both are valid activities, just be sure to notice which it is that you are doing and don't pretend to be doing one when you are really doing the other.
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Again, not my composition, but it does have my full endorsement. Enjoy the music! Charlie
