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

[waynel]

All too often, the problems with comparing sample rates is the use of not-linear phase filters, and the various group delay characteristics of the filters. A not-linear phase brickwall can have effects well into the audio spectrum, but they are not level differences, they are TIMING and propagation differences. Linear phase (constant delay) are absolutely necessary for controlling the experiment, unless all group delay errors have been compensated. (If this very general, and almost non-technical statement isn't clearly understood with nuance, then don't bother trying to do an experiment. This can be subtle stuff, and strange/erroneous results are very easy to achieve.)

The measurements must be controlled, and done with very careful engineering (I mean, DSP/human factors researcher level and defended), because there are so many variables (including human hearing changing vs time, and a 5-15 second accurate memory for many people.) Gotta understand some statistics also -- making sure that when there ARE random errors, they are at least partially filtered. Biased results (e.g. ham-handed choice of rate conversion software), doesn't help increase the knowlege base for anyone.

I don't mean to sound critical, but I have seen a lot of arguments that even I (just a fairly/reasonably knowlegable DSP person, writing really innovative software, but not the biggest expert in the world) can legitimately be critical and argue away many/most claims about high res sample rates. That doesn't mean that high res sample rates are never useful -- because they are, but not really in linear applications like presentation/playout. As long as you have 48k (I don't like 44.1k for emotional bias reasons), you are able to provide whatever human ears can receive. (Well, I don't like hiss either, and prefer wiggle room, so at least 16bits is best.) If you are doing ANYTHING nonlinear, then it is a good thing to have wiggle room (almost literally) in the sample rate, and usually 96k is a good choice, but I can almost always get by with 66.15k or 72k to save CPU and filter taps.

John

I haven’t seen any reliable study showing that humans can hear the difference between linear phase and non linear phase filters at 20kHz.

 

[todayamerican]

All rebuttals updated in the main article.

 

[John Dyson]

I haven’t seen any reliable study showing that humans can hear the difference between linear phase and non linear phase filters at 20kHz.

Time delays vs freq.... TImes of arrival. In the margins there could be a prolbem. It is more of a problem of mixing filters -- it can be a mess, best just to use linear phase and be done with it.

not-linear phase means variable group delay, which means varialbe time of arrival... it is plausible that people can hear when time coherency of material is distorted. But, it isn't at all about hearing above 20kHz at all.

I use linear phase filters in my work by default, because the results can be summed without phase/cancellation/timing problems. With not-linear phase, it is a real mess and a lot more work. I do more things than just brickwall, even though I do rate conversion when I need it (no libraries needed, but I choose my sample rates most of the time.

I do agree that there are specious arguments about the 'ringing' when filtering composite waveforms (like square waves) -- becuase it aint' ringing, those wobbles represent missing frequency components, that is it. (Gibbs) The fact that the wobbles move around, that means that the timing is skewed. I advise against using something that is more of an intellectual curiousity and not really useful -- not-linear phase adds too many variables.

(I do this stuff all of the time, and don't like complications. Some people enjoy sophistry and tweaking -- but I dont.)


John

 

[pkane]

All rebuttals updated in the main article.

Don't see any real rebuttal. The claim about "perfect" reproduction is a red herring: there's no such thing, and none possible. A perfect reproduction within the limits of normal human hearing is possible, and can be achieved with non-hires recording. If you're recording for audiophile babies, then sure, use 88KHz or 96KHz for best results. Otherwise, 48k should be plenty sufficient for the rest of us.

 

[John Dyson]

Don't see any real rebuttal. The claim about "perfect" reproduction is a red herring: there's no such thing, and none possible. A perfect reproduction within the limits of normal human hearing is possible, and can be achieved with non-hires recording. If you're recording for audiophile babies, then sure, use 88KHz or 96KHz for best results. Otherwise, 48k should be plenty sufficient for the rest of us.

Oh so true, especially when most consumer recordings (even these Telarcs that I am playing with right now) are heavly compressed to the tune of approx 20dB at high frequencies. I have produced 44.1k/16bit CDs that are audibly more clean than an equivalent HiRes 'premum' recording.

People are buying compressed stuff anyway. This 20+kHz is all about angels on the head of a pin. Ever seen a NRed spectrum? See all of that variable fuzz up there? That isn't mostly audio -- that is modulated hiss on most older pop recordings. (Even premium stuff.)

Better is nice, but a lot more quality could be attained if the recording distributors wouldn't be doing so much damage (even from the beginning of CDs.)

John

 

[Pluto]

would be interesting to hear what you think about this article

Tedious. Ranting. Preaching.

ultimately dull.

 

[tmtomh]

Article too stupid for productive discussion in my opinion.

This is the correct response.

 

[Pluto]

This is the correct response.

I don't mind a contentious, provocative article even if it is somewhat bereft of facts as long as it is entertaining and has something original to say.

This one does not.

 

[bennetng]

It's a waste of time going back and forth between a forum thread and a blog. May the author join ASR and have a deeper discussion? Also my ublock origin's block counter keeps increasing as long as that website's window remains open, a clickbait website? Highly disturbing.

As for the DSD nonsense on that website, here are my replies:
https://www.audiosciencereview.com/...es-dsd-sound-better-than-pcm.5700/post-128714
https://www.audiosciencereview.com/...ds/new-dac-chipset-from-akm.14391/post-454955

 

[Sgt. Ear Ache]

It's a waste of time going back and forth between a forum thread and a blog. May the author join ASR and have a deeper discussion?

I suspect he already has lol

 

[Feanor]

Has anyone explained this yet? I'm stone deaf above 10kHz, so a couple of things really ...

First, what relevance is there to me of anything above 10kHz much less anything above 20kHz?

Second, how come I can still hear pretty fine differences among, say, amplifiers? (0r is that all just my imagination?)

Third, how come I'm able to enjoy music?

 

[Sgt. Ear Ache]

Has anyone explained this yet? I'm stone deaf above 10kHz, so a couple of things really ...

First, what relevance is there to me of anything above 10kHz much less anything above 20kHz?

Second, how come I can still hear pretty fine differences among, say, amplifiers? (0r is that all just my imagination?)

Third, how come I'm able to enjoy music?

Well, to offer brief answers to your queries I'd say

1 - If you can't hear above 10khz, probably no relevance at all.

2 - oh here we go! lol

3 - an awful lot of what makes music music happens below 10khz.

 

[Jimbob54]

Well, to offer brief answers to your queries I'd say

1 - If you can't hear above 10khz, probably no relevance at all.

2 - oh here we go! lol

3 - an awful lot of what makes music music happens below 10khz.

Has anyone explained this yet? I'm stone deaf above 10kHz, so a couple of things really ...

First, what relevance is there to me of anything above 10kHz much less anything above 20kHz?

Second, how come I can still hear pretty fine differences among, say, amplifiers? (0r is that all just my imagination?)

Third, how come I'm able to enjoy music?

2. Because they measure significantly differently in reproducing sub 10khz frequencies OR you arent doing level matched double blind testing when comparing. Or both.

 

[bennetng]

I suspect he already has lol

Confirmed. This guy just opened another thread on General Audio Discussions and pointed to another blog with the same author, and refused to directly reply on the forum. Most likely for SEO or ads. Maybe @Thomas savage can do something about it.

 

[Thomas savage]

All rebuttals updated in the main article.

If your not intending to have a discussion here then I'm inclined to delete all this and ban your account.

 

[RayDunzl]

I want to hear the authentic reproduction of cymbals!!

Sorry, this is all I've got:

 

[Feanor]

...
2. Because they measure significantly differently in reproducing sub 10khz frequencies OR you arent doing level matched double blind testing when comparing. Or both.

That is, in response to my question, "If I'm deaf above 10kHz ... how come I can still hear subtle differences between amplifier?"

I think the answer is that there are sub-10kHz measurable differences. I'm not a person who says that measurements are irrelevant.

Your second part is superfluous given so many people are willing to attest from personal experience that amplifiers DO sound different, (albeit more or less different depending on the amplifiers). There is a certainly contradiction in case of people who insist on the primacy of measurements but then insist that all reasonably decent amps sound the same apart from playback volume differences

 

[Feanor]

Well, to offer brief answers to your queries I'd say

1 - If you can't hear above 10khz, probably no relevance at all.

2 - oh here we go! lol

3 - an awful lot of what makes music music happens below 10khz.

Certainly most music is below 10kHz including most of the timbre of almost all instruments. And for that matter, most of music is well above 20Hz apart from sound effects.

 

[Jimbob54]

That is, in response to my question, "If I'm deaf above 10kHz ... how come I can still hear subtle differences between amplifier?"

I think the answer is that there are sub-10kHz measurable differences. I'm not a person who says that measurements are irrelevant.

Your second part is superfluous given so many people are willing to attest from personal experience that amplifiers DO sound different, (albeit more or less different depending on the amplifiers). There is a certainly contradiction in case of people who insist on the primacy of measurements but then insist that all reasonably decent amps sound the same apart from playback volume differences

No, there are 2 reasons why you perceive 2 amps sound different.

1. They measure differently and that difference is audible. OR
2. You didnt do your comparison properly.

OR the explanation is a mixture of both. Unless you have tested properly.

You cannot default to 1 without addressing 2. Unless you have the measurements .

 

[vavan]

May the author join ASR and have a deeper discussion?

It would be nice if more aes members such as aforementioned JOSHUA D. REISS joined asr and shared their opinions