By the way, Gary, be afraid of what you've started -- you do realise, I hope, that you're going to have to repeat that whole exercise using a top notch reel to reel as source ...


Frank
Frank
By the way, Gary, be afraid of what you've started -- you do realise, I hope, that you're going to have to repeat that whole exercise using a top notch reel to reel as source ...
Frank
The important thing was that everyone had a good time. With all the responses tallied and the results were 50.88% got the correct answers, it's the same as flipping a coin. I don't see that there is anything statistically significant here to learn from.
I hope you understood I meant just replacing the turntable in Gary's experiment with, say, a Studer R2R and comparing the playback from that with the same signal then going through an extra A/D, D/A conversion ...analog tape/ digital comparisons
Thanks for the information, Terry. Gary and I had exchanged posts about "double backs" at the beginning of this thread. Of course, it's easy for me to say what I would have liked as an armchair quarterback here.Ron,
I'm not Gary, but I was very interested in the testing protocol, as I was rather involved in experimental design some years ago. There were no sighted tests performed. As the source (TT/LP) was the same, only the LED display would have indicated which configuration we were hearing at the time. The equipment was hidden behind an acoustic panel and even then, the gear faced away from the attendees. Whenever a change was requested, Gary made the switch using his remote and changed the display sign that indicated "A" or "B". It was for the listener to decide which (A or B) was analog and which was digital. There were no "double backs" using analog/analog or digital/digital.
Best Regards,
Terry Olson
If you were testing for a preference a global result would have some meaning. As most listeners do not get a statistic valid number of positive identifications, preference is meaningless.
But if you are testing for audibility of the AD-DA chain the good results obtained by the trained listeners suggest that the double conversion was audible, although the number of tests is then low. It will be very interesting to read their comments!
But if you are testing for audibility of the AD-DA chain the good results obtained by the trained listeners suggest that the double conversion was audible,
I don't think so. If I'm not mistaken, 73% is not enough to indicate more than chance in this number of trials, so what you have is one participant in 20 who correctly identified the samples enough to be indicative of anything. You also have 20 participants, 187 trials and a 50/50 rate of identification. I'm not sure anything has been indicated, statistically speaking, but if it has, at this point it's that the differences are not audible. What has been proven, at least to my satisfaction, is that it doesn't matter, and that the most sensible participants figured that out and started enjoying the music pretty quickly.
Tim
Many people share the idea that listening tests carried with untrained listeners have very limited reliability
But not with this number of trials and not with two "experienced" listeners out of 20. Equal numbers of listeners and trials would be required to even make a valid differentiation between experienced and inexperienced. So we're left with the numbers from 20 listeners in 187 trials with 50% identification. Only two conclusions can be reached: 1) that the "test" was not sufficiently controlled to be statistically meaningful. 2) That if it indicates anything, it is that the differences between the samples were inaudible. But by introducing the uncontrolled variable of the experienced listener in numbers far too small to be useful and totally out of balance with the rest of the test, we've left ourselves were we probably all want to be anyway -- free to continue believing what we want to believe.BTW 73% is a very good score in these type of tests - it would show a significant identification.
This was a hobbyist study and not anything intended to withstand scientific scrutiny. Having stated this, what stands out so far as others have noted is the difference between trained (2) versus untrained (18) listeners.
Gary, what tracks did you play which comprised the 23 (and 45) reports of no difference? What tracks did you play where the trained listeners did report accurately?
By the way, Gary, be afraid of what you've started -- you do realise, I hope, that you're going to have to repeat that whole exercise using a top notch reel to reel as source ...
Frank
Thanks for the information, Terry. Gary and I had exchanged posts about "double backs" at the beginning of this thread. Of course, it's easy for me to say what I would have liked as an armchair quarterback here.I wish I was there. I'm quite sure I would be drinking a pint of humility.
I don't think so. If I'm not mistaken, 73% is not enough to indicate more than chance in this number of trials, so what you have is one participant in 20 who correctly identified the samples enough to be indicative of anything. You also have 20 participants, 187 trials and a 50/50 rate of identification. I'm not sure anything has been indicated, statistically speaking, but if it has, at this point it's that the differences are not audible. What has been proven, at least to my satisfaction, is that it doesn't matter, and that the most sensible participants figured that out and started enjoying the music pretty quickly.
Tim
He got both mono recordings wrong - may be he was a bad guesser, but there was no soundstage to comment on.
we still don't know how to measure if a system is able to deliver a "wider soundstage" or what parameter it is that reduces the soundstage when the A/D/A loop is inserted.
A room without absorption at the reflection points will create its own sound stage, though of course that should remain constant as other things in the playback chain are changed.
On stereo material channel crosstalk can affect sound stage. Background noise could also have an affect if it's loud enough to drown out subtle reverb tails etc that are different on each channel.
--Ethan
In this case, since we are adding a A/D/A loop, crosstalk and background noise are not issues unless the ADC and/or DAC increase channel crosstalk or add noise.
Great line!Digital has just finished taking the CD player down the path of the 8-track.
They do, though the data gathered by Sean Olive at Harman, the only valid data on the question that I'm aware of, indicates that untrained listeners are reliable, and reach the same conclusions as the trained listeners (and these are formally trained, not just experienced audiophiles or studio pros), they just take longer to get there.
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