Charles, I'll cite a couple of the things that I have cited in the past here and might be informative and amusing to you. The
Stereo Review amplifier tests which enraged some audiophiles, but opened the eyes(and ears)of others, still are unchallenged(i.e. unchallenged by contrary results from later tests, not simply by a stubborn refusal to accept facts)and illustrate the contrast between some rather flowery language used to describe sound differences in open listening before the tests and the actual blind test results. Among other notable results was that the $220 Pioneer receiver was indistinguishable from the $12,000 pair of tube amplifiers.
Our Alan has been involved in many blind test sessions and you might find interesting this report of the
testing that defeated Ivor Tiefenbrun of Linn where Alan was present(still wonder if he ever got his watch back).
On whether the listeners know if a change actually has been made, this isn't necessary, but the ABX test method requires an actual change from A to B before trying to determine which of them X is. A different blind procedure, same/different, does sometimes have the same unit played for both samples, and a fair amount of the time the listeners incorrectly mark the same as being different.
One amusing incident that speaker designer John Dunlavy has occasionally recounted on the internet occurred when in a supposedly non-blind comparison between regular lamp cord and a very expensive boutique speaker wire, the "technician" behind the speakers apparently busily making switches actually left the lampcord connected at all times. One of the several "experts" present at Dunlavy's test, after the expensive cable was supposedly switched in, commented to him: "Omigod John, tell me that even you can hear that difference".
In one of Dr. Toole's excellent
papers which touches on the necessity of blind listening tests(at one AES meeting where he spoke on the subject, he stated, using a bit of hyperbole, that "If you can see what you're listening to, you can't hear it!")he shows at p.10 that even when items where differences actually exist, i.e. speakers, are involved, "huge" differences in open listening are greatly narrowed when the labels and price tags disappear and the listening becomes blind.
