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Failing to ABX but measurable physical response?

Some years ago I was filmed during an ABX test.

  • The ABX test showed that I didn't hear any difference between an audio file and the same file being played with a VST enabled.
  • The video recording showed that at certain playback positions my eyes wandered from the right to the left speaker and vice versa.

With my involuntary eye movements I reacted physically unintentionally to changes in the stereo image, the manipulation of which corresponds to the function of the VST (phase shifting at low frequencies). On the other hand, the ABX test showed that I hear no difference.

The question of how to assess this situation has been on my mind for some time now.

Any thoughts on that?

Re: Failing to ABX but measurable physical response?

Reply #1 –
If your eyes go left with every "A" or every "B" I'd say that's significant (if there's a significant number of trials).    But if you couldn't reliably hear a difference then I'm not sure what your eyes are reacting to...

It might be worth repeating the test...  Maybe if you repeat the test you could "pass" if you pay attention to what your eyes are doing, but I doubt it.

And, I'm not sure what the point is of a VST effect that doesn't have an obviously audible effect.

Re: Failing to ABX but measurable physical response?

Reply #2 –
I would probably question how the ABX test was conducted.  Some so-called ABX tests are not even single blind.

Re: Failing to ABX but measurable physical response?

Reply #3 –
Quote from: Maurus on
With my involuntary eye movements I reacted physically unintentionally to changes in the stereo image
How do you know that?
Loudspeaker manufacturer

Re: Failing to ABX but measurable physical response?

Reply #4 –
Quote from: dc2bluelight on
I would probably question how the ABX test was conducted.  Some so-called ABX tests are not even single blind.
 
 
My test wouldn't have met the requirements HA places on such a test. When I performed it, I neither knew HA nor did I even know what ABXing means. Plus, I also no longer have the video recording and the test file available. I wrestled with myself for a long time to see if I could dare to post my question on HA under these circumstances, but it just doesn't leave me alone.

Details see below, please.

Re: Failing to ABX but measurable physical response?

Reply #5 –
Quote from: DVDdoug on
...
 
 
@DVDdoug,

thank you for your prompt reply. I use AI for translations and since I don't speak English, I wouldn't notice any translation errors. So please let me know if something appears unclear to you.

My initial situation in more detail:

I tried to make listening to some clipped audio files more pleasant by using VST ReLife. My [not backed up by any test] impression was that with it the clipping would indeed be reduced, but I felt sometimes irritated by a very short acoustic disturbance of whatever kind, which I could not have described in any more detail, maybe because of its shortness (fraction of a second?).

Thereupon a second person played one of the files through my stereo unit and enabled or disabled the plugin without me seeing it, and I should say "off" or "on," depending on the VST's assumed activation status. During that, a video camera pointed at me happened to be running.

Not once could I say for sure when the plugin was enabled, so with my very limited knowledge of ABX I think I would not have passed an ABX test performed under the conditions required by HA. But I was aware that during this test I looked up a few times and looked from one speaker to another because some unexpected auditory event had caught my attention. These eye movements were taken by the camera.

Later on I searched the Internet for a description of the VST ReLife and found this statement from Alexey Lukin:

Quote
"I've just figured out that ReLife is an all-pass (i.e. phase-shifing) filter, it does not do any change to the frequency response. It shifts phase at low frequencies."
 

DVDdoug said:

Quote
But if you couldn't reliably hear a difference then I'm not sure what your eyes are reacting to...
 
That's the question that's bothering me, and why I wasn't be able to ABX it. The audio files were not clipped throughout, but there were only short volume peaks to which clipping applied. I wonder if my eye movements could have been unwitting/instinctive/spontaneous/automatic [correct translation?] reactions to the phase shifts described by Alexey Lukin.

And with regard to the failing ABXing:

Could perhaps the threshold value for the perception of phase shifts be so low that it is below the threshold value which triggers an active pressing of the buttons "A" or "B", but be high enough to explain these passive eye movements?

I apologize for my poor English. Especially when it comes to technical terms or accurat descriptions, I'm afraid of being hard to understand.

Re: Failing to ABX but measurable physical response?

Reply #6 –
It sounds like post hoc confirmation bias.

You weren't testing for eye movement and you didn't take any of the necessary steps to properly measure that type of data without introducing bias.
 

Re: Failing to ABX but measurable physical response?

Reply #7 –
Quote from: Maurus on
With my involuntary eye movements I reacted physically unintentionally to changes in the stereo image.

I wonder if my eye movements could have been unwitting/instinctive/spontaneous/automatic [correct translation?] reactions to the phase shifts described by Alexey Lukin.
You either heard the "phase shifts" or you didn't. You didn't "see" them, despite the post test speculation.
Speculation is self explanatory.
Loudspeaker manufacturer
 
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