Ethan Winer has long argued against the audibility of absolute polarity, with the basic claim that the only reason why some people hear it under some circumstances, has to do with nonlinearity in loudspeakers. In an early post on the subject, he provides some interesting test files.
More recently, however, Winer has updated this view with the fact that nonlinearity in the ear itself (and not the brain, btw) can make absolute polarity audible. The IMD created within the ear varies with sound pressure level. He has some newer test files that demonstrate this view, and show that it is not the brain doing this.
In my opinion, the best research ever done was published in the Journal of the Audio Engineering Society in the 1980's by Lipschitz and others. The demonstrated that audio polarity was marginally audible. It could be heard on test tones, or on recorded solo trombone on headphones and only on headphones. (The trombone has one of the more asymmetric waveforms.) On speakers, the differences between tests tones could be heard, but nothing else. In no case was polarity clearly audible on more complex music.
Of course, high end audiophiles are interested in things marginally audible, though it should not be our primary focus.
But Ethan's later view suggests that individuals with greater hearing nonlinearity might be more affected by absolute polarity than others. Nonlinearity probably correlates well with age and exposure related hearing loss. So cranky old audiophiles who insist absolute polarity is one of the most important things in audio reproduction could have a point--for themselves!
However, all my attempts to prove the audibility of polarity changes on a cranky old audiophile who insists absolute polarity is the most important thing in audio ended in failure (despite the subject being 100% confident). So in most cases, I still believe sighted testing bias is probably the best best explanation, as it likely is for most audio beliefs not founded in objective audio engineering and double blind validated audio science.
Sighted testing bias is a variant of expectation bias that applies to audio testing whenever people have independent means (which might not be concurrent) of establishing the test conditions. Expectation bias is easy enough to understand--you get what you expect. But often in audio, people didn't actually know what to expect until later, so they may argue that their expectations were not important. Here the problem may actually be cherry picking results that fit an expected result. Then people may argue they didn't have any such expectations beforehand, so how could they cherry pick results to match. But if they only performed a limited number of sighted tests, the effect is similar to cherry picking, they simply stop testing when their final tests and expectations match. Audio is extremely vulnerable to this as it is well established we may never hear the same stimulus exactly the same way twice. For that reason, audio science requires Double Blind Testing, where the tested person has no way of knowing the test conditions during the test, and repeats the test a predetermined number of times with accuracy reaching statistical significance.
All this testing is hard work, and I don't do it much myself. But I don't claim to be re-inventing audio science either...I more or less accept generally accepted audio science results, only with the small disclaimer that small enough differences may be subject to false negative test results. So there might be currently unexpected differences, but they would only likely be very small and usually unimportant. Audiophiles are typically claiming the reverse, transcendent improvements in every recording from changes that have no basis in audio science or engineering. Claims like this are best doubted until further validation.
My main area of "quackery" concernts the effect of ultrasonics past my 16kHz hearing limit. I believe they are important. But I often, myself, wonder if this is actually true.
Other than that, I am mostly merely trying to achieve ordinarily accepted audio engineering principles, such as wide bandwidth, low distortion, and low noise.
I always try to maintain correct absolute polarity. It's probably not a big deal, but it's an objective detail which might as well be correct. However I don't obsess over each piece of equipment or every recording--to find the optimal polarity for it. In my experience, very few pieces of digital equipment have inverted polarity, and not many analog equipment either.
The only digital piece of equipment I'd ever known which reversed audio polarity was an iPod. I've tested many disk players by Sony, Denon, Pioneer, and Integra, and not found one that inverted polarity, contrary to claims of a friend of mine. (Who then surmises they have circuits to detect and correct polarity on test signals.)
Perhaps until just now. The new equipment I am still investigating, it could be unusually important in the annals of absolute polarity...
More recently, however, Winer has updated this view with the fact that nonlinearity in the ear itself (and not the brain, btw) can make absolute polarity audible. The IMD created within the ear varies with sound pressure level. He has some newer test files that demonstrate this view, and show that it is not the brain doing this.
In my opinion, the best research ever done was published in the Journal of the Audio Engineering Society in the 1980's by Lipschitz and others. The demonstrated that audio polarity was marginally audible. It could be heard on test tones, or on recorded solo trombone on headphones and only on headphones. (The trombone has one of the more asymmetric waveforms.) On speakers, the differences between tests tones could be heard, but nothing else. In no case was polarity clearly audible on more complex music.
Of course, high end audiophiles are interested in things marginally audible, though it should not be our primary focus.
But Ethan's later view suggests that individuals with greater hearing nonlinearity might be more affected by absolute polarity than others. Nonlinearity probably correlates well with age and exposure related hearing loss. So cranky old audiophiles who insist absolute polarity is one of the most important things in audio reproduction could have a point--for themselves!
However, all my attempts to prove the audibility of polarity changes on a cranky old audiophile who insists absolute polarity is the most important thing in audio ended in failure (despite the subject being 100% confident). So in most cases, I still believe sighted testing bias is probably the best best explanation, as it likely is for most audio beliefs not founded in objective audio engineering and double blind validated audio science.
Sighted testing bias is a variant of expectation bias that applies to audio testing whenever people have independent means (which might not be concurrent) of establishing the test conditions. Expectation bias is easy enough to understand--you get what you expect. But often in audio, people didn't actually know what to expect until later, so they may argue that their expectations were not important. Here the problem may actually be cherry picking results that fit an expected result. Then people may argue they didn't have any such expectations beforehand, so how could they cherry pick results to match. But if they only performed a limited number of sighted tests, the effect is similar to cherry picking, they simply stop testing when their final tests and expectations match. Audio is extremely vulnerable to this as it is well established we may never hear the same stimulus exactly the same way twice. For that reason, audio science requires Double Blind Testing, where the tested person has no way of knowing the test conditions during the test, and repeats the test a predetermined number of times with accuracy reaching statistical significance.
All this testing is hard work, and I don't do it much myself. But I don't claim to be re-inventing audio science either...I more or less accept generally accepted audio science results, only with the small disclaimer that small enough differences may be subject to false negative test results. So there might be currently unexpected differences, but they would only likely be very small and usually unimportant. Audiophiles are typically claiming the reverse, transcendent improvements in every recording from changes that have no basis in audio science or engineering. Claims like this are best doubted until further validation.
My main area of "quackery" concernts the effect of ultrasonics past my 16kHz hearing limit. I believe they are important. But I often, myself, wonder if this is actually true.
Other than that, I am mostly merely trying to achieve ordinarily accepted audio engineering principles, such as wide bandwidth, low distortion, and low noise.
I always try to maintain correct absolute polarity. It's probably not a big deal, but it's an objective detail which might as well be correct. However I don't obsess over each piece of equipment or every recording--to find the optimal polarity for it. In my experience, very few pieces of digital equipment have inverted polarity, and not many analog equipment either.
The only digital piece of equipment I'd ever known which reversed audio polarity was an iPod. I've tested many disk players by Sony, Denon, Pioneer, and Integra, and not found one that inverted polarity, contrary to claims of a friend of mine. (Who then surmises they have circuits to detect and correct polarity on test signals.)
Perhaps until just now. The new equipment I am still investigating, it could be unusually important in the annals of absolute polarity...
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