Do you believe in Magic?

psychophysics is a discipline within the field of psychology.

its principles are applicable to detecting differences between the sound of components.

two terms to consider are adaptation level and differential threshold.

i'll try to be brief.

the differential threshold applies to detecting differences in spl, e.g. . how much of a change in spl is necessary to detect differences in loudness, varies from person to person.

adaptation level concerns the point at which the nervous system is no longer efficient, because neurons are firing more slowly, fatigue sets in and perception of differences suffers. there are actions to be taken to avoid reaching the adaptation level, otherwise, errors in judgment will occur.

i would prefer not to get too technical or sound like a lecturer.

i hope i have at least given an indication of the importance of these principles and anyone who sees value in their application should read about psychophysics in psychology text books.

Mrtennis wrote,

"the differential threshold applies to detecting differences in spl, e.g. . how much of a change in spl is necessary to detect differences in loudness, varies from person to person.

adaptation level concerns the point at which the nervous system is no longer efficient, because neurons are firing more slowly, fatigue sets in and perception of differences suffers. there are actions to be taken to avoid reaching the adaptation level, otherwise, errors in judgment will occur."

Thanks for the explanation.

One can't help wondering if this loss of efficiency by the nervous system is why blinds tests that require many consecutive trials might be unreliable. And why some proponents of blind tests as final arbiters of high end speakers, cables and tweaks *require* a large number of trials, if you see what I mean.

let me add two other caveats:

human beings are subject to two errors in perception, i.e., omission and commission.

sometimes we fail to hear what is on a recording and other times we ascribe information to a recording which is not there.

let me give an example which you can try yourself.

there is a cd "jazz at the pawn shop". one of the tracks is "lady be good". somewhere under one minute from the beginning of the track a telephone rings. the spl is much lower than the sound of the instruments.

my friend and i listened to the cd on two different stereo systems and could not hear the telephone. obviously, the ring tone is somewhere in the upper mids/lower treble.

a third person heard the ring. thus aural acuity varies among listeners.

another example is claiming to hear three guitars, and consulting the liner notes, finding out that there are only two guitarists.

there is an important lesson here. one should not consider the results of listening as knowledge , as sense perception is inherently unreliable.

Mrtennis, having taken as many courses in psychology in pursuing my doctorate as in political science, I am well aware of perceptual errors. I am also aware that human beings' senses have served them well in survival, with hearing being central to this. I also think this has little relevance to picking an audio component that suits your taste.

In your post where I thought you were seemingly a scientist and not an engineer, you seemed to suggest that mankind does not fully understand everything that shapes our ability to reproduce music in our rooms. Many EEs believe that what they learned prohibits differences in power cords, isolation, and even amplifiers, which personally I find ridiculous. I see no reason to criticize someone for liking a particular component or power cord even if I think it is worthless. It is his taste and money. Unreliable or not, his perceptions are what counts. And obviously we all differ, or there would be very few manufacturers as many products would have been found most unsatisfactory, and their makers having gone out of business.

Mrtennis wrote,

"there is a cd "jazz at the pawn shop". one of the tracks is "lady be good". somewhere under one minute from the beginning of the track a telephone rings. the spl is much lower than the sound of the instruments.

my friend and i listened to the cd on two different stereo systems and could not hear the telephone. obviously, the ring tone is somewhere in the upper mids/lower treble.

a third person heard the ring. thus aural acuity varies among listeners."

This doesn't appear to be headline news. Was there ever any doubt that aural acuity varies among listeners?