Having studied the psychology of drafting surveys and performing
blind experiments, I find your survey flawed. It's not a
blind test if you have told us which is which (that is unless you're lying to us about which is which -- a valid approach under normal conditions, but one that doesn't apply here). Even if you're lying to us about which is which, the fact that people
think they know which is which may
skew your results with predispositions they have towards one or the other type of cable.
What you'll end up with are people who respond thinking "I think that clip X15 must be
star-quad cable because it sounds better than clip X16, and
star-quad cables always sounds better." That, instead of, "I think it's _____, because it sounded most like the ______ reference at the beginning of the audio file."
Rather than asking which we think is which for questions 1-10, I think the relevant questions more appropriately are 11-18. I do not see how questions 1-10 could produce any variety of conclusive data.
Another concern is how complicated the test is. "Oh, but it's so easy to listen to an audio clip that's 13 minutes long and check some radio buttons on a form." Yes, it is, but to perform the test in a way that yields consistent data, people should be comparing each X clip to the references and stating which they think was better, not which they thought was which type of cable. Suddenly a 15-minute survey is 35 minutes. Many people will be exhausted listening to the clips by the time they reach X03 or X04, trying to discern which is which. By the time they get to X10, they're just ready to check an option -- any option. They want to move on and be done with it.
If I was performing the experiment, I would record the
Conventional Cable and
Star Quad Cable clips, have someone not connected to the project rename the files Cable X and Cable Y, not telling me which is which until I've received survey results and have come to a conclusion that people think Cable X sounds better or Cable Y sounds better. Only after I've come to a conclusion with the data would I find out from the person who changed the file names which was which -- eliminating potential for
bias from both the survey participants as well as myself as the experimenter.
I would skip the X1-X10 tests completely; the really conclusive data comes from your Y and Z clips, but by the time people get that far in the survey, they'll check any box they can just to be done with it. They've also spent the first 10 questions confusing themselves on which they think is which.
As a matter of form, I'd also avoid radio buttons as people have a tendency to just click one or the other without much thinking. Some will click the top option because it's the first one, and others will just deliberately mix up their results to make it look like they tried -- especially happens when people are not confident they've been able to discern a difference and end up just guessing. Having people typing in Z or Y makes it less friendly having to analyze the results afterwards, but survey participants are more likely to make an educated decision when they have to consciously decide which letter to type.
Personally, I would participate if it was just Y and Z, but I have no interest in attempting to answer the first ten required questions because: 1) I believe they produce skewed results, 2) It takes a long time and I'll drive myself nuts attempting to discern a difference, and 3) There's no option to participate in just the Y and Z comparison without either suffering through the first 10 questions or just clicking random radio buttons to get to the part of the survey that I think matters.
You've certainly given this survey and this topic more thought than I have, so maybe you have valid reasons for the way you're doing it that I haven't considered, but if I think you'll find more conclusive, credible, and consistent data as well as more participants by cutting it down to just the Y and Z clips for comparison. It'd also be less hassle for people to download because it could be a 35MB audio instead of 216MB, 2 minutes to listen to instead of an absolute minimum of 15 (a more
practical minimum of 20-30 for those that really want to do the survey well).