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Audiophiles Rejoice: The Nyquist–Shannon sampling theorem actually proves high-res audio is real and works

pkane

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https://link.medium.com/ktiNtRo1m8

I like ASR, would be interesting to hear what you think about this article.

So the sum total of the argument is that there are some sounds with frequencies above 20kHz and if you don’t reproduce them, then the reproduction is not perfect.

OK, so what? Why should I care? I don’t listen to frequencies above 20kHz. And I will not hear them even in a ‘perfect’, original analog signal. So why should I care that they are not reproduced?
 

whazzup

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From the article:
Sound is vibration. Sure, you can only hear from 20Hz to 20 KHz of that vibration. Sure, if you listen “only” to sounds above 20 KHz, you will not hear anything. Problem is, many trained musicians & studio engineers can experience the effects of vibrations above and below what humans can hear, when the signal is played back. I can tell you that I can hear nuances of guitar music when it is played back live vs. a recording — because I learnt guitar for 12 years. The brain is trained to recognize the full authenticity of a received signal, even if “hearing” consists of only some parts of the signal.

So can people really be trained to 'feel' the vibration above 20k? Not a musician / audio engineer, so I'm curious about the validity of this statement. Does that also mean they'll respond to me when I use a dog whistle?
 

Alexanderc

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My understanding (from things I’ve read here) is, below 20hz, yes absolutely. Above 20khz? I can’t imagine that would feel like vibration, maybe pressure. I’m not a headphone guy, so maybe??
 

Alexanderc

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It’s certainly not written with an academic tone or sensibilities. Plus the grammar errors…

Edit: I wasn’t planning to read the whole thing, but it was just too entertaining. Some of this is not just wild exaggeration but patently false. Also, someone should teach him what an appendix is and how to use one.
 
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DonH56

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I only got through part of it... If you buy his argument, then any rolloff less than infinity means some signal will be lost, whether the signal is sampled or not. By that argument, no audio component up to and including (especially) the speaker can accurately reproduce the original signal. Assuming you somehow magically manage to record that sort of bandwidth. And I am not sure why the repeated emphasis on not being able to hear above 20 kHz and yet accurate reproduction requires it...
 

617

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Article too stupid for productive discussion in my opinion.
 

MRC01

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I can think of 2 reasons to use higher sampling rates. Neither is mentioned by that article, which focuses on irrelevant points. Indeed, his argument applies to analog recording too, since it also is bandwidth limited. In many cases, the microphones are the bandwidth limit, not the recording medium. However we record, it's always bandwidth limited. What is the point of recording at 192 kHz to get Nyquist to 96 k, if the mic itself doesn't capture anything above 30 k? Another important point he fails to mention is the energy or amplitude of those frequences around 20 kHz is very small (with most sounds anyway) and often masked by the much louder sounds at lower frequencies. So if they get attenuated, perceptually, most of the time, it doesn't make a big difference.

So why use higher sampling rates?

First, because they allow a gentler anti-aliasing filter. At 44.1 k sampling, the transition band is only 20,000 to 22,050. That's a narrow range for a filter to go from 0 to -infinity, hard to do in real-time with limited hardware without passband artifacts. Higher sampling rates give a wider transition band, gentler slope, which is easier to implement. Evidence of this is how common it is for DACs measured here to have filters that extend the transition band to 24 k, which is above Nyquist at 44.1 k sampling. They wouldn't cheat like this unless they had a reason... If we used a sampling rate even just a little higher, like 48 k, they wouldn't have to cheat.

Second because some people, with some audio signals, under ideal conditions, can detect the difference between 44.1k and higher sampling rates. A while back, Amir posted one such ABX test that he did. I believe the test signal was jangling keys in front of a mic? It was either that or some other signal that had a lot of extreme HF content. Another study has been referenced here too, showing a small but not insignificant % of people detected signals in the range of 20k and slightly higher.

In suggesting that higher sampling rates have some benefit, I'm not saying we need to go crazy. 48 k would likely be sufficient. 88.2 k would be more than enough.
 
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waynel

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I feel stupider for reading that article. States without proof that humans can hear over 20kHz and calls everyone fools. Doesn’t disprove Nyquist- Shannon Theorem but a good example of the Dunning-Kruger effect!
 

Tks

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From the article:


So can people really be trained to 'feel' the vibration above 20k? Not a musician / audio engineer, so I'm curious about the validity of this statement. Does that also mean they'll respond to me when I use a dog whistle?

Not only that, this guy is out of his mind even logically... look at what he says what you quoted him for:

"Problem is, many trained musicians & studio engineers can experience the effects of vibrations above and below what humans can hear, when the signal is played back. I can tell you that I can hear nuances of guitar music when it is played back live vs. a recording — because I learnt guitar for 12 years."

First off, all those people he talks about are usually older people that can't hear 15K, let alone 20K.

Second, he equivocates (I can hear nuances of guitar music when played live VS recording).. What does this have to do with being a musician? Normal people can tell such differences, nuance doesn't say anything about hearing 20K..

Third, hearing nuance between live vs recorded does not mean you are capable of hearing 20K, that's not the only consideration simply because even in live you're not hearing 20K, so this whole theory falls on it's face and the back of it's head.

Finally, you played guitar for 12 years? So on top of probably being in your late twenties at best, or late thirties.. Most musicians, especially live performers, actually lose their hearing quite a bit more than regular folk. So sure, while he can probably pick out notes and tonality better than normal people (as any trained musician also could), his "hearing ability" because he's "played for so long" would actually be an argument against his hearing senses the older he gets, ESPECIALLY if he performs live or things of that nature.

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Just a terrible article which is par for the course for many on Medium.
 

Daverz

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So why use higher sampling rates?

First, because they allow a gentler anti-aliasing filter.

It allows for a gentler anti-aliasing filter on the analog input, but I think digital downsampling and dither algorithms are good enough that 44.1kHz/16 bit is probably sufficient for the playback format.
 

DChenery

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It allows for a gentler anti-aliasing filter on the analog input, but I think digital downsampling and dither algorithms are good enough that 44.1kHz/16 bit is probably sufficient for the playback format.

For a great example, look at the filter developed by Topping on the D10s that was just reviewed (23/07/2020). Flat to 20K and then drops to -78 dBrA by 22.1K. Does almost exactly what the theory requests without any fuss or muss.

As a side note, took 10 posts to invoke the Monty! Have seen Monty used as early as 3 posts, and as late as 20 pages in. :)
 

Blumlein 88

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For a great example, look at the filter developed by Topping on the D10s that was just reviewed (23/07/2020). Flat to 20K and then drops to -78 dBrA by 22.1K. Does almost exactly what the theory requests without any fuss or muss.

As a side note, took 10 posts to invoke the Monty! Have seen Monty used as early as 3 posts, and as late as 20 pages in. :)

Yes first response had I seen it would have been Monty.
 

whazzup

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Not only that, this guy is out of his mind even logically... look at what he says what you quoted him for:

"Problem is, many trained musicians & studio engineers can experience the effects of vibrations above and below what humans can hear, when the signal is played back. I can tell you that I can hear nuances of guitar music when it is played back live vs. a recording — because I learnt guitar for 12 years."

First off, all those people he talks about are usually older people that can't hear 15K, let alone 20K.

Second, he equivocates (I can hear nuances of guitar music when played live VS recording).. What does this have to do with being a musician? Normal people can tell such differences, nuance doesn't say anything about hearing 20K..

Third, hearing nuance between live vs recorded does not mean you are capable of hearing 20K, that's not the only consideration simply because even in live you're not hearing 20K, so this whole theory falls on it's face and the back of it's head.

Finally, you played guitar for 12 years? So on top of probably being in your late twenties at best, or late thirties.. Most musicians, especially live performers, actually lose their hearing quite a bit more than regular folk. So sure, while he can probably pick out notes and tonality better than normal people (as any trained musician also could), his "hearing ability" because he's "played for so long" would actually be an argument against his hearing senses the older he gets, ESPECIALLY if he performs live or things of that nature.

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Just a terrible article which is par for the course for many on Medium.

Playing devil's advocate:
https://www.cco.caltech.edu/~boyk/spectra/spectra.htm

The proportion of energy above 20 kilohertz is low for most instruments; but for one trumpet sample it is 2%; for another, 0.5%; for claves, 3.8%; for a speech sibilant, 1.7%; and for the cymbal crash, 40%. The cymbal's energy shows no sign of stopping at the measurement limit, so its percentage may be much higher.

I want to hear the authentic reproduction of cymbals!!
 

vavan

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So can people really be trained to 'feel' the vibration above 20k?
not sure about that but according to Joshua Reiss AES meta-analysis publication "The results are striking. The training subgroup reported an overall strong and significant ability to discriminate high resolution audio"
 

Blumlein 88

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Playing devil's advocate:
https://www.cco.caltech.edu/~boyk/spectra/spectra.htm



I want to hear the authentic reproduction of cymbals!!
You can't. Your biological construction has betrayed you.

I can bash a pizza pan with spoons and get significant energy to 50 khz, but human people can't hear it.

Have some keys on a keyring in your pocket? Bring them out and jangle them. The majority of the energy is above 20 khz and pretty loud. It will sound like a soft tinkle to you all the same.

Sorry mate you've got human limitations.
 
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