[csglinux]

Of course a signal that has a discontinuity will never appear in real life using acoustic instruments, and would not meet the requirements of being bandwidth limited for sampling theory. This will be taken care of with the Davina project decimation filter - and I have two filters designed. As too the DAC side, with a M scaler and Dave, there will be no extra ringing whatsoever, as it will reconstruct the un-sampled signal to a better than 16 bit accuracy under all conditions. But we still have the ringing in the decimation filters to worry about.

Now sampling theory is very clear - you must use a sinc function filter to perfectly reconstruct a perfectly bandwidth limited sampled signal; but sampling theory says nothing about how that bandwidth limiting occurs, it just states that at FS/2 and greater there must be zero signal energy. I have designed two filters - an IIR type, and an FIR type, both with >250 dB rejection at FS/2 and above. The IIR type will have no pre-ringing, but is phase non-linear. The FIR type is phase linear, but has lots of pre-ringing. Which one will sound more like no filtering at all? I will know when the listening tests starts, and we will be able to answer this question completely. My guess is that bandwidth limiting with FIR will be close to completely transparent, as I see the pre-ringing issue at 22.05 kHz as a complete red-herring. The filters have been designed to bandwidth limit but preserve the 705 kHz sample rate, so one will hear only the effect of bandwidth limiting.

The test files will be published too, so people can listen for themselves on a 768 kHz capable DAC.

Thanks Rob. Looking forward to hearing those test files

 

[Rob Watts]

not planning to be Sound Science ambassador as I'm merely the incompetent mall cop of the section(also if we're a lobby, where is the money?!!!!!!!!), but I at least have personal issues with some subjective stuff you say and their more or less intuitive implications on human hearing. about the objective part of your posts, I'm usually in agreement with you and honestly learned a good deal from you over the years. so more than ever, I find important to properly separate objective and subjective conversation.

I can believe in the possibility that changes in the settings of very extreme stuff, noise shapers or anything else, could end up having various consequences at the output signal. some maybe less expected than others depending on gear and processing.
and if some of those consequences manifest at audible levels, then of course I believe that you could hear them. presented that way there is nothing too strange about your anecdotes. except you're never telling them that way. instead you use those anecdotes to repeatedly suggest that human hearing goes way beyond what the actual knowledge on the subject would consider realistic. let's say something like this with simple stimuli for starters http://www2.bcs.rochester.edu/courses/crsinf/221/13.pdf and maybe this about masking which is so very relevant if you're going to make alusion at audible stuff down by 300dB http://www2.bcs.rochester.edu/courses/crsinf/221/14.pdf

if you actually have an experience demonstrating the need to revise the boundaries of what we consider human hearing, then obviously you should describe it exhaustively so that other people would point out your mistakes, or maybe replicate your findings and help the facts be clearly established. instead, you suggesting extraordinary stuff in a perfectly casual way, makes me think that you're talking from sighted impressions(and then anything goes), or that you're only doing this for marketing effect. in which case, can you really blame me for thinking that the all super hearing idea is making as much sense as the scenario of Sharknado3?


about sampling and reconstruction, now I'm with you and math. although I have little care for extreme tap length because it's a lot of efforts for very small improvement. at the same time, so long as it's not detrimental to other stuff, I can't really complain about you trying to increase accuracy ^_^. so as I said, on the objective side of things, we're unsurprisingly good. in general, clean cut for higher fidelity within the band limited range and as little out of band crap as possible, that's pretty rational to me.
on the other hand, most brands advocating that good sound is a good looking Dirac pulse are IMO willingly misleading consumers with that visual trickery. it's the same abuse of intuitive but false demonstration that has been used so often by showing a staircase signal in a graph. when I see those stuff my trust in the brand instantly drops to zero and I move into my "skeptical whiner" mode AKA Monday morning.

Hmmm - you talk about human hearing, but I don't actually talk about human hearing - I talk about perception. They are very different things. Hearing implies the abilities of the ear, and as you correctly state is very limited from psycho-acoustic testing, as the ear as a transducer is a poor device. Perception, on the other hand, is about the brain processing the information from the ears to create the audio illusion that we enjoy; perceiving individual sounds as discrete entities with each entity having it's own timbre, and placement location is a trick or illusion that the brain performs; it is not data from the ears, but a perceptual illusion created by the brain. Moreover, science has little understanding of how the brain performs this processing. And psycho-acoustic testing has nothing to say about the engineering requirements to perceive depth, instruments as separate entities, or individual instruments range of timbre; no research has been done on this at all. Psycho-acoustics actually is very simple, involving simple single tones - and we can't base our design requirements on such simple tests.

To give you an analogy; the ear performs like a 16 bit system - 96 dB dynamic range, 20 kHz bandwidth. Assume we have a system with peaks at +96 dB SPL and the ear can't resolve individual sine waves below 0dB SPL, and the traditional engineering view is that the system does not need to be concerned about signals below -96 dB (that's at 0dB SPL) as the ear can't perceive them anyway.

But put that signal thru an FFT, and now we can see signals buried in the noise; and with an infinite FFT window, we can see signals to infinitely small levels, if we wait an infinite amount of time... Now the brain does not do FFT's, but it is thought that correlation routines are used in perception - and correlation can be similarly used to expose signals well below noise. And I have had many instances where I can perceive the effect of errors even when those errors are too small to be audible directly. So if you had silence, with just the errors playing, it would be impossible to hear the errors; but mixed in with the music it is possible to perceive the effect of those errors; and the reason that they become audible is because they interfere with the brains correlation process that is used to perceive sound; and these correlation processes are working to a much greater accuracy than the ears performance.

And yes I do, as you say, "you suggesting extraordinary stuff in a perfectly casual way" because I don't care about the postings I make to whether people believe me or not. I do many listening tests, repeated on different occasions, and am confident in my outcomes. My listening tests are not about proving 100% that something exists to other people; they are about proving to me that something is audible and important - I am solely concerned about making better sound quality, and making progress towards truly transparent performance. Indeed, if my postings were about persuading people then I would not be so stupid as to post that stuff at -350 dB is important, as this is just plain absurd levels of accuracy. It's akin to homeopathy when dilution is down to one active molecule per litre, which would be absurd a claim to make that that level is important.

And before you say sighted listening tests, confirmation and expectation bias, placebo etc - yes sure these are very powerful things, and must be removed or taken into account when performing listening tests. And I do plenty of tests, where I can hear no nett change whatsoever (and get into trouble when posting about these results). And yes, when something extraordinary comes along I do perform single blind tests too.

Just to conclude with an anecdote; In the past I created and patented IP that was sold to large semiconductor companies; and my contracts with these companies meant I had to embed the IP into the corporations staff, so a lot of my role was education. And often I would get into big arguments with extremely clever and educated scientists, mathematicians and engineers; and these arguments would centre on something being done a particular way for better sound quality. After several years of this, I felt like I was getting nowhere, so decided to show one of their engineers the difference in sound quality. So I invited him to my home and did some listening tests. One of the tests had a -180dB noise shaper, against a -200dB noise shaper. Both offered perfect performance from a measurement or hearing psycho-acoustic POV. The engineer was not an audiophile, and I conducted the tests single blind. He could readily hear the difference; afterwards he told me that what surprised him was not that he could hear the difference (as he trusted that I was not making this stuff up) but that how easy it was to hear these differences - it was a night and day change to him. He duly filed his report to the company, and thereafter I had no arguments as to whether something was important subjectively or not.

 

[musickid]

Amazing stuff Rob. 'Not everything that can be counted counts and not everything that counts can be counted' Albert Einstein.

 

[bhobba]

I felt like I was getting nowhere,

You are not the only one mate. The highly respected speaker designer George Short who has a Masters degree in speaker design from Virginia Tech had exactly the same issue. Theory told him one thing - actual listening another. He was employed by many of the great speaker makers of the time such as Acoustic Research. He designed speakers to sound good from listening - evidently others were not as enamored with that approach and he formed his own company, now defunct, called North Creek Audio and designed speakers his way. For example he believed small gauge (such as 9 gauge) air cored inductors sounded best so used those. Many of his peers thought him mad but his ears told him the truth so that's what he used. He is retired now of course.

Thanks
Bill

 

[dmance]

@Rob Watts
Fascinating stuff. Rob.
I recently added supertweeters to my setup (TakeT Batpro 2). Like your listening tests, nothing is audible when the batpro is played alone ...but when played in conjunction with the main speakers, it's quite audible that there is information added. The steep transient notes have more clarity and realism: strings, female voice, snare drum, trumpet, etc. Also ambient venue sounds just stand out: claps, whistles, room echo, etc.

All obvious pleasure from signals that we are not supposed to be able to hear. So the knowledge of how the ear/brain really works at both low energy and high frequency is just lacking
Can't wait for Davina to spur new research here...

 

[dac64]

@Rob Watts
Fascinating stuff. Rob.
I recently added supertweeters to my setup (TakeT Batpro 2). Like your listening tests, nothing is audible when the batpro is played alone ...but when played in conjunction with the main speakers, it's quite audible that there is information added. The steep transient notes have more clarity and realism: strings, female voice, snare drum, trumpet, etc. Also ambient venue sounds just stand out: claps, whistles, room echo, etc.

All obvious pleasure from signals that we are not supposed to be able to hear. So the knowledge of how the ear/brain really works at both low energy and high frequency is just lacking
Can't wait for Davina to spur new research here...

Well! Even adding a subwoofer will affect the ultrahigh frequency. In fact, the whole spectrum wiil be affected by those unmeasurable frequency decay from the sub.

Or improve the bass response, through speaker placement, from the system also have the same effect.

The flater the low is, the better the extension of high frequency.

 

[JaZZ]

Or vice-versa: During my speaker-builder «career» I often experienced that a tweeter fine-tuning can improve the bass.

Great post, Rob! One could argue that the human hearing doesn't just consist of the ears, but include the part of the brain that's responsible for signal decoding. Also, if the ears weren't sensitive enough to capture the mentioned ultra-subtle cues, the brain couldn't decode them – hence they can't be that bad. However, that doesn't derogate your argumentation in the least.

 

[dac64]

Or vice-versa: During my speaker-builder «career» I often experienced that a tweeter fine-tuning can improve the bass.

Yeah boy! Now I recalled that my friend ever told me that the bass was also improved after he fine-tuned the position of a pair of super tweeters. I was surprised then!

 

[Peter Hyatt]

Rob, would you opine here?

I am technology challenged.

I have Hugo 2 and use Auditvana from MacBook Pro. Beyerdynamic T1.


I love it.


New Dylan release in November.

I don’t think I will be able to land M Scaler for Hugo 2. I do think I’ll get 2Go.

Is it better for me to get 24/96 download than to buy the CDs since I have no transport? I only rip into Mac.

Thank you.

 

[514077]

Rob, would you opine here?

I am technology challenged.

I have Hugo 2 and use Auditvana from MacBook Pro. Beyerdynamic T1.


I love it.


New Dylan release in November.

I don’t think I will be able to land M Scaler for Hugo 2. I do think I’ll get 2Go.

Is it better for me to get 24/96 download than to buy the CDs since I have no transport? I only rip into Mac.

Thank you.

I'm not Rob, but I'll jump in. I usually go for the higher-res download, unless I can find out the mastering history of the tracks. e.g. Once, I bought a DSD128 version of an album-some Gershwin and other stuf-only to read the tracknotes right in front of me on the webpage from which I bought it. Turned out it was mastered at 24/96, and that was what I should've gotten. If I knew this Dylan album was directly taken from a 24/96 master, that's what I'd buy.
I know most people-followers might say; "you have a Chord DAC, 44.1K is all you need." I'm not a techno whiz, nor a code-master. But, I'm a customer who gets tired of adjenda-based columns or posts. Why not take a chance and grab them both and test it out? I think that's what my, uh, adjenda boils down to.

 

[Rob Watts]

Yes go for the original bit perfect master, particularly if it's 96k, as sample rate conversion and decimation to 44.1 is not good on SQ. That said, an M scaled at 705k from 44.1 will beat a 96k source that has not been M scaled...

 

[Peter Hyatt]

Thank you, both.

 

[castleofargh]

Hmmm - you talk about human hearing, but I don't actually talk about human hearing - I talk about perception. They are very different things. Hearing implies the abilities of the ear, and as you correctly state is very limited from psycho-acoustic testing, as the ear as a transducer is a poor device. Perception, on the other hand, is about the brain processing the information from the ears to create the audio illusion that we enjoy; perceiving individual sounds as discrete entities with each entity having it's own timbre, and placement location is a trick or illusion that the brain performs; it is not data from the ears, but a perceptual illusion created by the brain. Moreover, science has little understanding of how the brain performs this processing. And psycho-acoustic testing has nothing to say about the engineering requirements to perceive depth, instruments as separate entities, or individual instruments range of timbre; no research has been done on this at all. Psycho-acoustics actually is very simple, involving simple single tones - and we can't base our design requirements on such simple tests.

To give you an analogy; the ear performs like a 16 bit system - 96 dB dynamic range, 20 kHz bandwidth. Assume we have a system with peaks at +96 dB SPL and the ear can't resolve individual sine waves below 0dB SPL, and the traditional engineering view is that the system does not need to be concerned about signals below -96 dB (that's at 0dB SPL) as the ear can't perceive them anyway.

But put that signal thru an FFT, and now we can see signals buried in the noise; and with an infinite FFT window, we can see signals to infinitely small levels, if we wait an infinite amount of time... Now the brain does not do FFT's, but it is thought that correlation routines are used in perception - and correlation can be similarly used to expose signals well below noise. And I have had many instances where I can perceive the effect of errors even when those errors are too small to be audible directly. So if you had silence, with just the errors playing, it would be impossible to hear the errors; but mixed in with the music it is possible to perceive the effect of those errors; and the reason that they become audible is because they interfere with the brains correlation process that is used to perceive sound; and these correlation processes are working to a much greater accuracy than the ears performance.

And yes I do, as you say, "you suggesting extraordinary stuff in a perfectly casual way" because I don't care about the postings I make to whether people believe me or not. I do many listening tests, repeated on different occasions, and am confident in my outcomes. My listening tests are not about proving 100% that something exists to other people; they are about proving to me that something is audible and important - I am solely concerned about making better sound quality, and making progress towards truly transparent performance. Indeed, if my postings were about persuading people then I would not be so stupid as to post that stuff at -350 dB is important, as this is just plain absurd levels of accuracy. It's akin to homeopathy when dilution is down to one active molecule per litre, which would be absurd a claim to make that that level is important.

And before you say sighted listening tests, confirmation and expectation bias, placebo etc - yes sure these are very powerful things, and must be removed or taken into account when performing listening tests. And I do plenty of tests, where I can hear no nett change whatsoever (and get into trouble when posting about these results). And yes, when something extraordinary comes along I do perform single blind tests too.

Just to conclude with an anecdote; In the past I created and patented IP that was sold to large semiconductor companies; and my contracts with these companies meant I had to embed the IP into the corporations staff, so a lot of my role was education. And often I would get into big arguments with extremely clever and educated scientists, mathematicians and engineers; and these arguments would center on something being done a particular way for better sound quality. After several years of this, I felt like I was getting nowhere, so decided to show one of their engineers the difference in sound quality. So I invited him to my home and did some listening tests. One of the tests had a -180dB noise shaper, against a -200dB noise shaper. Both offered perfect performance from a measurement or hearing psycho-acoustic POV. The engineer was not an audiophile, and I conducted the tests single blind. He could readily hear the difference; afterwards he told me that what surprised him was not that he could hear the difference (as he trusted that I was not making this stuff up) but that how easy it was to hear these differences - it was a night and day change to him. He duly filed his report to the company, and thereafter I had no arguments as to whether something was important subjectively or not.

I think understand all your points, some I even agree with. others I really don't. but most of all, your anecdotes can't possibly be conclusive of anything to me because of how little I actually know of them. but I'm tempted to guess that the most likely explanations might not be the ones you decided to come up with. perhaps your beliefs on the subject make you less skeptical about potential errors in the test or more importantly, the interpretation of it. but from where I stand, I couldn't satisfy myself with that sort of anecdote, given the world changing nature of the implications if all was correct. with noise shaping, I'd probably start wondering about the possible impact of the energy moved at higher freqs, and would want to measure the hell out of the analog output, and probably try other gears to check what role they might have to play in this.
but mainly I simply can't reconcile how ineffective the attempts to conclusively demonstrate the audibility of high res have been, with concepts where stuff at -200dB would be easily audible. that paradox alone kills the deal for me.

yes the brain does amazing stuff, and after all psycho acoustic is full of examples where altering just one variable can have a global impact on perception with often non intuitive relations, like how a FR change can impact impressions of dynamic, speed, position in space... so your ideas are very fair IMO, expect when it comes to the magnitudes you consider relevant. that just doesn't agree with any research I've seen.
I get the idea that a signal alone at -300dB might not have the same impact as that signal added to a clearly audible sound. from a concept of censor, there could be something too small for the minimum sensitivity of the censor to even react. but having it "carried" by a higher amplitude signal may or may not make the difference between 2 values for the resulting voltage or whatever quantization of it. I can't argue with the idea and possibility. but again I disagree with the magnitudes involved for the human ear. and I also disagree because acoustic masking directly contradicts your views on at least one aspect of sound variations at lower amplitudes. let alone the variation in signal, auditory masking "erases" the lowest magnitude information and makes it like it never existed in the first place for the listener so changing what isn't heard is not going to create much of an impression. and it's not just the brain deciding to pretend like he doesn't get the data, a concrete part of that lost signal has to do with the cochlea and purely mechanical and chemical reasons. even how the masking extends more toward higher frequencies, agrees with physics and how a loud low frequency signal is shaking everything in the area closer to the entrance responsible for capturing upper freqs. while high freqs dissipate rapidly so they have a hard time exiting the areas for lower frequency signals. it's pretty straightforward physic and suggest a loss of lower amplitude data because of higher amplitude signal.

there is also typical body noises, or simply cells firing up on their own as they apparently do, and ambient noise of course, making it impossible to just assume that everything will count and be taken into account by the brain as part of the music. all that exists as data, but is probably disregarded as noise and filtered out by the brain.

also there is complexity of the signal. a stimulus alone is more detectable than mixed in music(pretty much all hearing tests agree with that and give a JND much worst while the signal is within complex musical content instead of isolated. so practical situations also disagree with the idea of small changes in music being easily noticed. far from possibly letting us perceive stuff changing at -200dB, they won't even let us perceive stuff we could notice if they were heard alone.
in general just thinking about the necessary changes in the signal to give the perception of a different direction by even a tiny value like say 1°, or the variation in amplitude for us to notice a change from loudness(a little above 0.1dB under great conditions). first we realize that such variations while potentially noticeable on occasions, are not stuff that would really influence our experience of the music. who cares if the guitar is 1° more on the left? even trying to stay still, I'm surely going to move my head by more than 1° over the length of the track. those are anecdotal examples, but they both constitute unimportant changes while still being many magnitudes over anything going on at -200dB. yet stuff happening that low would somehow noticeably influence our impressions of the "room" in a relevant way? again my problem isn't with the ideas but with the magnitudes.

also as I've mentioned before, right or wrong, you have one luck, your vision aligns with trying to get higher objective fidelity. ^_^ which is never a bad idea. on the other hand, the guys who believe that massive aliasing in exchange of no ringing is improvement, they better have designed something that sounds subjectively nice, because objectively they really screwed up.

 

[bhobba]

Wouldn't looking over measurements invariably convince you that the product "sounds like the measurements"

Of course not. Why would you believe that? Reading about the Carver challenge and what he had to do to get two amps to sound the same shows why:
https://www.stereophile.com/content/carver-challenge

He could not get them to sound the same by measurements alone, but he also had to use a nulling technique.

Thanks
Bill

 

[Jawed]

On your way

back to my ghetto

you might like to listen to the original music and 12 variants using different upsampling filters:

https://www.computeraudiophile.com/forums/topic/49630-16x-filter-test-results/

as you might hear some differences. You might even be motivated to explain why you do or don't hear differences.

Now playing: Låpsley - Falling Short