kml
Sensei
King o' lamp cord
Posts: 235
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Post by kml on Mar 5, 2013 23:27:22 GMT -5
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Post by arthurz on Mar 5, 2013 23:56:16 GMT -5
Great video! Thanks for sharing.
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Post by yves on Mar 6, 2013 7:40:38 GMT -5
I agree this video is MUCH more explanatory than that article that claimed 192 kHz music downloads make no sense. However, it still fails to address the undeniable fact substantial evidence found in modern auditory neuroscience indicates severe flaws in our age-old understanding of what's audible under what circumstances and what isn't, as well as the fact inaudible sounds affect brain activity in such way they become part of our listening experience as they alter our perceptions. Our ability to discern differences in the frequency domain is TEN TIMES more accurate than Fourier analysis and likely about a hundred times more sensitive than a thirty-year-old oscilloscope. Hair cells PHYSICALLY react to nerve impulses coming from the brain. Think about that for a moment when you hear someone say oh it's more than 100 dB below the music so it SHOULD be inaudible.
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Post by arthurz on Mar 6, 2013 21:12:55 GMT -5
Our ability to discern differences in the frequency domain is TEN TIMES more accurate than Fourier analysis Interesting. Do you have a source for that? Are they talking about transients? How is this related the the audibility of –100 dB? I mean you can see a –100 dB peak in the frequency domain. |
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Post by garym on Mar 6, 2013 22:20:22 GMT -5
However, it still fails to address the undeniable fact substantial evidence found in modern auditory neuroscience indicates severe flaws in our age-old understanding of what's audible under what circumstances . . . What evidence? What kind of evidence? A link to a source would be appreciated. Actually, they react to sound waves coming from the environment. The brain reacts to the nerve impulses they generate. |
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Post by yves on Mar 9, 2013 6:11:50 GMT -5
[quote author=arthurz board=tech thread=29433 post=501777 time=1362622375[/quote]
How is this related the the audibility of –100 dB?[/quote]
There are alot of people who think any digital artifact that's like 100 dB or so below the music will be completely masked out by the loudness of the music itself, or will fade into the distant landscape. I claim BS on that. To get you an idea of how incredibly sensitive the human hearing system actually CAN be, humans can hear the difference between tones that are as little as 1 Hz apart.
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Post by yves on Mar 9, 2013 6:19:05 GMT -5
Actually, they react to sound waves coming from the environment. The brain reacts to the nerve impulses they generate. Try reading science mags (like Nature, for example). Hair cells do not react only to sound waves, but also to the nerve impulses they receive from the brain. |
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Post by garym on Mar 9, 2013 12:51:17 GMT -5
Try reading science mags (like Nature, for example). Hair cells do not react only to sound waves, but also to the nerve impulses they receive from the brain. Have a cite to a specific article? And to the evidence you mentioned above? |
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Post by yves on Mar 9, 2013 13:51:06 GMT -5
Have a cite to a specific article? And to the evidence you mentioned above? Like I said, start reading true magazines like Nature. I have zero interest in discussions with people who have a proven agenda of almost uninterruptedly choosing to minimize and ignore latest advancements in auditory neuroscience and psychoacoustics. |
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Post by garym on Mar 9, 2013 19:17:48 GMT -5
Have a cite to a specific article? And to the evidence you mentioned above? Like I said, start reading true magazines like Nature. I have zero interest in discussions with people who have a proven agenda of almost uninterruptedly choosing to minimize and ignore latest advancements in auditory neuroscience and psychoacoustics. Apparently no interest in substantiating your claims, either.  |
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Post by yves on Mar 10, 2013 1:35:10 GMT -5
Like I said, start reading true magazines like Nature. I have zero interest in discussions with people who have a proven agenda of almost uninterruptedly choosing to minimize and ignore latest advancements in auditory neuroscience and psychoacoustics. Apparently no interest in substantiating your claims, either. Efferent projections from the brain to the cochlea also play a role in the perception of sound. Efferent synapses occur on outer hair cells and on afferent (towards the brain) dendrites under inner hair cells. The presynaptic terminal bouton is filled with vesicles containing acetylcholine and a neuropeptide called Calcitonin gene-related peptide (CGRP). The effects of these compounds varies, in some hair cells the acetylcholine hyperpolarized the cell, which reduces the sensitivity of the cochlea locally. en.wikipedia.org/wiki/Hair_cellen.wikipedia.org/wiki/Efferent_nerve_fiber |
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Post by arthurz on Mar 10, 2013 13:06:20 GMT -5
What's the connection to the audibility of -100 dB SPL?
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Post by yves on Mar 10, 2013 15:43:31 GMT -5
What's the connection to the audibility of -100 dB SPL? That was only an example I used to illustrate my point, and I didn't say -100 dB SPL, but 100 dB below the music. While it is true the fact loud music masks out small digital artifacts for the most part, that doesn't also mean the ones that aren't fully masked out are of little or no importance sonically. Worse still, the Xiph.org video completely ignores the logical relationship between inaccuracies of an audio signal in the digital domain and their effect on sound quality as perceived by humans. |
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Post by arthurz on Mar 10, 2013 19:36:59 GMT -5
Sorry, Yves, of course not –100 db SPL  . Even if your music was playing at 100 dB SBL, noise 100 dB below it would be at the audibility threshold of 0 dB (at the absolute threshold, so even assuming the music wasn't there, you could only hear it in an acoustically treated room). Agreed that digital has artifacts, but aren't they spread evenly throughout the spectrum? Doesn't seem any worse (and in fact much better) than all analog sources I can think of. |
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Post by yves on Mar 11, 2013 6:54:28 GMT -5
Agreed that digital has artifacts, but aren't they spread evenly throughout the spectrum? Doesn't seem any worse (and in fact much better) than all analog sources I can think of. That's my whole point to begin with. On a measurement plot it seems like digital artifacts are way too small to lose any sleep over them. However, their measured size says little or nothing about their value in terms of audibility by humans, let alone in terms of musical impact. The measured distortion caused by vacuum tubes is preposterously huge compared to that of a 16-bit 44.1 kHz CD, yet there are people who prefer listening to 24-bit 192 kHz digital recordings through vacuum tubes regardless. There is not a linear relationship between the measured accuracy of an audio signal and the perceived sound quality or musical satisfaction this accuracy engenders. I have heard several thousands of audio CDs, and not a single one of them comes even remotely close to the sound quality of the best LPs. As for 24-bit 96 kHz (and 192 kHz) digital, yes of course it sounds much better than vinyl records, but then not all music is available in digital Hi Res... Worse, even when it is available anyway after all, it still very often falls short compared to vinyl mostly due to p!$$ poor mastering. |
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Post by garym on Mar 11, 2013 10:14:35 GMT -5
On a measurement plot it seems like digital artifacts are way too small to lose any sleep over them. However, their measured size says little or nothing about their value in terms of audibility by humans . . . . Correct. To determine whether they are audible you need to do ABX testing. You might find this of interest: www.computeraudiophile.com/blogs/mitchco/16-44-vs-24-192-experiment-163/No doubt. That simply tells you that some people prefer distorted signals to clean ones. Probably because they have become accustomed to the former and accept it as "normal." True, for the reason above. |
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KeithL
Administrator 
Posts: 10,273
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Post by KeithL on Mar 11, 2013 10:43:30 GMT -5
This is very interesting - and Audio DiffMaker is a useful tool... but there seems to be some serious misunderstanding about what it demonstrates. DiffMaker is designed to make the differences between two different signals obvious. The purpose of this is to analyze and compare the magnitude of those differences. (If we listen for the differences between, say, two compressed files and the original, we can easily tell which is less different from the original, and so tell which is the most accurate copy.) This does NOT, however, in any way tell us how audible each of the differences we are comparing are. I can take two "20 foot planks", lay them next to each other, and easily see that one is 1/8" longer than the other (this is what DiffMaker does). However, this in no way suggests whether that 1/8" difference is visible under other circumstances. On a measurement plot it seems like digital artifacts are way too small to lose any sleep over them. However, their measured size says little or nothing about their value in terms of audibility by humans . . . . Correct. To determine whether they are audible you need to do ABX testing. You might find this of interest: www.computeraudiophile.com/blogs/mitchco/16-44-vs-24-192-experiment-163/No doubt. That simply tells you that some people prefer distorted signals to clean ones. Probably because they have become accustomed to the former and accept it as "normal." True, for the reason above. |
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KeithL
Administrator
Posts: 10,273
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Post by KeithL on Mar 11, 2013 11:34:53 GMT -5
I am thoroughly confused with your comment about Fourier analysis. Fourier analysis is a mathematical process performed on data. It is as accurate as the original data and the computational accuracy at which it is performed. As such, it can be as accurate as you like - with no limit whatsoever. In contrast, our ability to recognize differences in the frequency domain does indeed have some measurable limit. The ability of we humans to SEE distortion on an oscilloscope trace (by actually looking at the shape of the wave) is limited to distortion over about 5% in most cases. ALL statements about noise masking and such are heavily dependent on the conditions under which they are measured. Compression schemes like MP3 and Vorbis were worked out with the intent that MOST PEOPLE WOULDN'T NOTICE THE DIFFERENCE WITH MOST MUSIC. Nobody, including in most cases the inventors, would actually suggest that there was no difference audible to anyone with any source material. However, if you want to evaluate the "viability" of digital music reproduction, you must also consider the limitations of ALL the alternatives. Is it possible to distinguish a digital artifact that is at -100 dB below full scale? Personally I suspect that it probably is not... but maybe it's possible. (Are we turning the gain up so loud that a 0 dB signal would kill us? If so, is that a "reasonable circumstance" under which to compare things?) What I can say for certain is that, if our sample were recorded on a vinyl record instead, that signal at -100 dB would be BURIED 30 dB BELOW THE RECORD SURFACE NOISE... And a typical CD has a THD in the 0.00x% range, whereas a record is probably in the single digit percentages at higher recording levels (with luck). So, are you suggesting that a digital system, with a really good S/N ratio, and some artifacts at -100 dB that might or might not be audible to some people, isn't superior to an analog recording, where we KNOW that there is a noise floor at only -70 dB, which is audible to everyone? Or are you suggesting that the 0.003% THD on a DAC is MORE audible than the much higher level of THD that you get from vinyl. I would agree that characterizing anything as "perfect" is going a bit too far, but it seems obvious to me that digital has gotten way closer than analog.... and that it also has the potential to get even closer (while analog technology is pretty well "maxxed out"). As for feedback from the brain adjusting the sensitivity of the receptors in your ear... it's been pretty well known for a long time that your brain/ear implement a form of dynamic range compression to improve sensitivity at low sound levels... when things get really quiet your ears get a lot more sensitive... and this sounds like they've finally worked out some details about how it occurs. I agree this video is MUCH more explanatory than that article that claimed 192 kHz music downloads make no sense. However, it still fails to address the undeniable fact substantial evidence found in modern auditory neuroscience indicates severe flaws in our age-old understanding of what's audible under what circumstances and what isn't, as well as the fact inaudible sounds affect brain activity in such way they become part of our listening experience as they alter our perceptions. Our ability to discern differences in the frequency domain is TEN TIMES more accurate than Fourier analysis and likely about a hundred times more sensitive than a thirty-year-old oscilloscope. Hair cells PHYSICALLY react to nerve impulses coming from the brain. Think about that for a moment when you hear someone say oh it's more than 100 dB below the music so it SHOULD be inaudible. |
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KeithL
Administrator
Posts: 10,273
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Post by KeithL on Mar 11, 2013 11:46:48 GMT -5
I agree with you that a lot of the music currently available isn't mastered very well. But you must remember that this has always been true. Just like most tube fanatics conveniently fail to remember all the pathetically BAD sounding tube amps that were out there fifty years ago, record lovers conveniently forget all the crummy sounding records. If anything, the drawback to digital audio is that, by making it easier and cheaper to make a recording, it encourages people to do so who are less than qualified. (When it cost $50k to master a record, at least that limited the number of total incompetents who were able to raise the money to do a pressing.) As for vacuum tubes, I think that there is simply a rather sad misunderstanding going on there. Tubes sound different because they make large amounts of second harmonic distortion. Most tube power amps also have very low damping factors, which makes them sound different in a different way (they interact differently with various speakers to produce different inaccuracies). Please understand that I have nothing against any of this, and happily defend the rights of tube lovers everywhere to choose the sound that they like. Let's just avoid muddying the waters by pretending that the difference isn't simply a coloration introduced by the tube equipment. (We age bourbon in oak barrels to get the flavor from the wood, and nobody complains about the wood mucking up the taste; this is the same thing; and not at all a bad thing - as long as we all understand the facts.) As for vinyl, my LEAST fond memories of vinyl include lots of record hiss, a few million crackles, and flinching every time a loud POP made me wonder if the damage was permanent or would come off with a good careful cleaning. I find it funny how record lovers never seem to remember THAT side of records. To me, a few pops per minute make a record downright unlistenable - no matter how good the quality of the audio between them. (And, yes, I know that, if you're very, very, VERY careful, you can avoid MOST of the pops... but not the surface noise.) Agreed that digital has artifacts, but aren't they spread evenly throughout the spectrum? Doesn't seem any worse (and in fact much better) than all analog sources I can think of. That's my whole point to begin with. On a measurement plot it seems like digital artifacts are way too small to lose any sleep over them. However, their measured size says little or nothing about their value in terms of audibility by humans, let alone in terms of musical impact. The measured distortion caused by vacuum tubes is preposterously huge compared to that of a 16-bit 44.1 kHz CD, yet there are people who prefer listening to 24-bit 192 kHz digital recordings through vacuum tubes regardless. There is not a linear relationship between the measured accuracy of an audio signal and the perceived sound quality or musical satisfaction this accuracy engenders. I have heard several thousands of audio CDs, and not a single one of them comes even remotely close to the sound quality of the best LPs. As for 24-bit 96 kHz (and 192 kHz) digital, yes of course it sounds much better than vinyl records, but then not all music is available in digital Hi Res... Worse, even when it is available anyway after all, it still very often falls short compared to vinyl mostly due to p!$$ poor mastering. |
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Post by garym on Mar 11, 2013 12:09:56 GMT -5
This does NOT, however, in any way tell us how audible each of the differences we are comparing are. Yes. That is why the author performed ABX testing on the differences computed by AudioDiffmaker. |
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. Even if your music was playing at 100 dB SBL, noise 100 dB below it would be at the audibility threshold of 0 dB (at the absolute threshold, so even assuming the music wasn't there, you could only hear it in an acoustically treated room).
