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  1. Old Comment

    Can a double blind test really be double blind?

    There are always issues like those discussed here when human subjectivity is involved. To some extent it may be helpful to approach the problem statistically. We could test many different people using one particular test, as is often done. Or if we are more interested in one specific individual, we could try using different tests at different times and under different circumstances. For some individuals we might see fairly consistent results, which in turn might give us more confidence about the reliability of our measurements for them. For individuals more at the other end of the spectrum, it may be harder to determine their abilities with much reliability or certainty, or how they might be likely to measure in the future.
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    Posted 28th December 2016 at 12:26 AM by Markw4 Markw4 is offline
  2. Old Comment
    jan.didden's Avatar

    Can a double blind test really be double blind?

    This is what SY has to say about it:

    "The unasked question: why does blind testing show fabulous sensitivity to tiny changes in level, frequency response, interchannel timing and localization...,? The issue isn't that ears only reduces sensitivity, there's too much data to the contrary; it's that it fails to confirm the magic differences that form high end marketing and the resulting audio lore. That's really the only controversy. This stuff is the usual excuse-making."
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    Posted 27th December 2016 at 07:20 PM by jan.didden jan.didden is online now
  3. Old Comment

    Can a double blind test really be double blind?

    there is neurophysical feedback between hearing and brain state, expectation of listening for differences along different acoustic perceptual axis like loud/soft, pitch, timbre, attack, timing...
    the Haas effect, a zoo of others can actually change the sensitivity of the inner ear sound to nerual impluse train transduction

    so yes, a subject who's expectation is primed for listening for a particular difference may be distracted from hearing a "clearly audible" difference along another axis

    the Gorrila suit walking past the basket ball players is a classic of perceptual focus, no reason to believe there isn't similar effects in our audio processing
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    Posted 27th December 2016 at 06:34 PM by jcx jcx is offline
  4. Old Comment
    jan.didden's Avatar

    Can a double blind test really be double blind?

    Yes, fully agree, my rambling is not about the first (or 2nd) double in double. I should have made clear it is about the test subject only, how he/she can be blind. The trust of my thinking is that this test subject may be cut off from all external sensory inputs except the sound, but does that make his/her listening 'blind'? Does that guarantee that the listening report is not influenced by anything except the sound?
    Knowing how devious a mind/brain really is, I doubt that.

    As an example, when doing the test you probably know where you are, the time of day (morning, afternoon, evening), probably the names of the people administering the test etc. There would be a clear link in your memory to similar events with the same people with some specific outcome. This may be enough to skew your judgement big time. Hence my question: can a (double or not) blind, controlled test really be blind in the sense that ONLY the sound matters?
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    Posted 27th December 2016 at 06:17 PM by jan.didden jan.didden is online now
  5. Old Comment

    Can a double blind test really be double blind?

    I think you are double thinking "double blind" giving it a meaning beyond its technical experimental use

    "double blind" simply means that that during a trial there is no other information channel for the subject to "read"

    specifically the 2nd "blind" in "double blind" is that the experimenter, anyone in the room or in any other communication with the test subject is also "single blind" as to the identity of the specific X trial A/B status

    this is to avoid the "Clever Hans" effect

    sound waves hitting ears and the best possible neural processing of that signal with training and focus ARE wanted if the question is can you hear the difference
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    Posted 27th December 2016 at 03:56 PM by jcx jcx is offline
  6. Old Comment
    SyncTronX's Avatar

    HP 339A Mods & Upgrades

    Moorepages are back

    Just to let everyone know the the Reverend Robin Moore (Dick's widow) has helped the Moorepages
    resserrection.

    The link in the HP339A blog works.

    Cheers,

    Sync
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    Posted 27th December 2016 at 03:50 PM by SyncTronX SyncTronX is offline
  7. Old Comment
    abraxalito's Avatar

    My latest infatuation - transformers

    The 1000uF is calculated not to roll off the bass too much - the load 'seen' by the cap is 4X (coz your trafo is 2:1) the speaker impedance. I did a quick LTSpice sim and it shows you get about 0.3dB loss at 20Hz from this value, nothing really noticeable subjectively. Having no DC on the trafo is most likely the cause of the perceived bass quantity improvement.
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    Posted 26th December 2016 at 07:12 AM by abraxalito abraxalito is offline
    Updated 26th December 2016 at 07:15 AM by abraxalito
  8. Old Comment
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    Posted 25th December 2016 at 10:03 PM by TNT TNT is online now
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