The most relavent quote:
"Moreover, my understanding of the literature is that so far it has only been experimentally detected under very strict listening conditions, very rarely with real CDs (much less Primus and consumer gear), and never on HA. Past discussions on the subject have not yielded a concrete conclusion, since nobody had really successfully ABX'd it."
Well, if thats what the "experts" say.
Now if I were an "expert" I would call all that a bunch of bunk.
And let's just accept it for now that reversed polarity is "detectable". Given that it is still "arguable" (the best anyone has been able to do is show that it is detectable under very strict conditions) it is a real stretch to call it a "significant" factor. I prefer to work on that those things that cannot be denied as significant - like imaging, and dynamics.
Hi Mat
No, not yet, really busy. I'm trying to do too many things at one time. I might have to give up sex!
Even if they are detectable, that doesn't mean to me that one is necessarily better than the other does it? I mean I suppose that it might be better with the polarity in line with how it was designed, but I don't see why it has to be that way.
Dan
Hi Dan, objectively it would be an issue since it is known that the hair cells fire only on a positive portion of the waveform. Thus switching positive for negative would not be "accurate" - IF it were audible.
"it is known that the hair cells fire only on a positive portion of the waveform."
Our ears are half-wave rectifiers?!
Or do the nerves also transmit when the hairs spring back, giving the other half of the wave, but perhaps a half cycle late depending on the phase?
Still the waveform getting to the brain (if that's even what gets sent to it) might be different depending on if the springback nerve impulse is the same as the initial one.
Our ears are half-wave rectifiers?!
Or do the nerves also transmit when the hairs spring back, giving the other half of the wave, but perhaps a half cycle late depending on the phase?
Still the waveform getting to the brain (if that's even what gets sent to it) might be different depending on if the springback nerve impulse is the same as the initial one.
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Yes, unless you use both. That's why I build my power supplies "by ear"
OK, enough of the one liners from me. That one was just bad.
Dan
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Yes the impulses are basically 1/2 wave rectifiers, but you have to remember that the information content is NOT coded in time as much as it is encoded in frequency. Basically the ear does not act like any transducer that I know of. I don't know all the details, it gets quite complex when you see a mapping of how the information is received,and emncoded to the brain. Then it becomes cognitive and things get really complex. I don't even suggest studying at this level of detail because it does add much to the understanding of audio.
Interesting.
OK, here's one for you, if you didn't already know it - I learned from my nephew, who's working on a phd in neuroscience, that our ears contain an array of sensing diaphragms tensioned by muscles.
The kicker is, the brain changes the tension and tunes them, so our hearing has a variable freq response!
That throws a lot of audiophile dogma on its head.
I meant to start a thread on that but never got around to it.
OK, here's one for you, if you didn't already know it - I learned from my nephew, who's working on a phd in neuroscience, that our ears contain an array of sensing diaphragms tensioned by muscles.
The kicker is, the brain changes the tension and tunes them, so our hearing has a variable freq response!
That throws a lot of audiophile dogma on its head.
I meant to start a thread on that but never got around to it.
Not quite right, but I can see where you got things wrong.
It's not "diaphragms" that are tensioned, but hair cells. And yes the tuning does change, but it doesn't change the frequency response, it changes the sensitivity at the frequency of those hairs. (Stop thinking time domain and think frequency domain. Each hair is sensitive to a specific frequency regardless of what frequency it is tuned at.) Our nuero-senses are only capable of about 60 dB range from the cell firing, but we have about 120 dB range to sound. The remaining 60 dB is done by mechanically tuning and detuning the physical system to keep it within the 60 dB range that the nuerons are capable of.
When these hairs break, what happens is that you loose the 120 dB range and it goes to 60. But there are other hairs cells that actually fire and when you loose those the 60 goes to 0. The first type of loss is called recruitment and you can hear just fine for loud sounds, but you lose soft ones. They are called inner and outer hairs cells, two banks of them. Thousands altogether.
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Wow! You were serious. That is some fascinating stuff. I still don't see how it would effect what we hear though--well except for nonlinearities which aren't particularly troublesome as far as I know with most speakers. You'll still have air compression and rarefaction either way.
Another A and P issue:
Anyone have a guess at how sensing ultrasound works? If it isn't the ear, how do we sense US let alone conduct it? Bone? I've heard of bone conduction from the protrusion behind the ear, but I'm not sure if that's an accurate description. If this is true, may this be a reason to get media and transducers capable of US output?
Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect -- Oohashi et al. 83 (6): 3548 -- Journal of Neurophysiology
Dr. Geddes, any flaws you see in this research method? I don't see any, but this isn't my thing at all. I know there are a few studies that disagree, but they were done a completely different way.
Dan
Sorry for going further off topic, but Anatomy, physiology, and Neurology is fun stuff. Worthy of its own thread but I'm not sure there is much expertise or real use for it around here.
That is some fascinating stuff. I still don't see how it would effect what we hear though--well except for nonlinearities which aren't particularly troublesome as far as I know with most speakers. You'll still have air compression and rarefaction either way. Another A and P issue:
Anyone have a guess at how sensing ultrasound works? If it isn't the ear, how do we sense US let alone conduct it? Bone? I've heard of bone conduction from the protrusion behind the ear, but I'm not sure if that's an accurate description. If this is true, may this be a reason to get media and transducers capable of US output?
Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect -- Oohashi et al. 83 (6): 3548 -- Journal of Neurophysiology
Dr. Geddes, any flaws you see in this research method? I don't see any, but this isn't my thing at all. I know there are a few studies that disagree, but they were done a completely different way.
Dan
Sorry for going further off topic, but Anatomy, physiology, and Neurology is fun stuff. Worthy of its own thread but I'm not sure there is much expertise or real use for it around here.
That's what I would say too
Markus
Except that was a typo!! I meant to say that these minute details don't add much to the concepts in audio. What we want to know is a far bigger macro scale that also includes the cognitive aspects. The details of cell firings don't correlate well with perception. They can help you to understand the "root cause" of some of the psychoacoustics, but its the psychoacoustics themselves that are the important features.
That's like saying there is no association between the brain and behavior.
I suspect you are trying to simplify things but this goes so far that it is incorrect.
A better way to put it would be to say that the firing of an individual neuron does not correlate strongly with perception. As you probably know, the ear, the retina, all sensory systems have massive amounts of parallel processing.
Also, can you provide a reference for the role of inner and outer hair cells in hearing loss? Your description is different from what i know about their function.
Finally, I also disagree with your faith in psycho acoustics. I believe, by understanding the cellular mechanism of a psycho acoustic phenomena, you will be given the necessary insight in how to manipulate it to advantage in loudspeaker design. In fact, I hope to make such a discovery some day.
That's my 2 cents.
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