Testing audiophile claims and myths

[Steve999]

There are - at least - two LP/vinyl threads on head-fi, running for a long, long time :

https://www.head-fi.org/threads/tur...t-a-new-thread-ask-your-question-here.613136/

https://www.head-fi.org/threads/post-a-photograph-of-your-turntable.549616/

TBH - vinyl is LOTS of hits and misses - the latter outnumbering the former, unfortunately. It is an EXTREMELY metiuculous way of doing things - whereas one can be "sloppy" with digital ( and everything can be backed up and/or restored - at least for the last whatever operation you did wrong ) - but EVERY mistake with things vinyl is final. It can range from ruined just one record ( learning the hard way in the least expensive way... ), trough breaking styli ( at "few" hundreds to "few" K a pop... ) - to the harshest one - realizing you have SNAFUed your entire record collection to FUBAR condition ...

It is MUCH more expensive than digital. Unless you plan to have at very least approx 10K for your entire rig ( sky is the upper limit ) - digital will always be a better choice. Records are the second most expensive sound carrier commercially available - after R2R second gen tapes. Record hygiene is THE biggest issue - and nobody should be without some serious record cleaning "device(s)".

I work with analog records and the equipment to play them on for 43 years , have MUCH more experience than most analog oriented audiophiles, yet I know that I know only a little. That said, I forgot about analog record playback probably more than 99% of people will ever know.

Currently in the process of figuring out how to digitise some 2-3K records - in a way that will result in a digital file that should be better sounding than possible with normal record playback, even when using the best possible equipment. In essence, bringing the sensation your kid experienced for the first time with vinyl even further - on a digital file, all while preserving the vinyl for the future with the minimal possible record wear.

It is a tall order - but, as it seems, doable.

I thought you my like a thread with your friends in sound science. I would like that. I started the thread with you in mind.

I had the best experience with Adobe software—powerful enough that you can really screw things up but also very easy to make improvements once you find your favorite tools. It is cool when it feels like you’re listening to the LP you know so well from a digital file. It’s also a good object lesson in exactly how powerful digital is. The interface runs along the Adobe paradigm so if you have experience with Adobe software you have a head start up the learning curve. Maybe it’s Adobe Audition? I think they bought it out from someone several years ago but it seems to me they are active in improving it. Well this is my last post about that out here in the wild as I don’t want to go too far OT. My thread is around if you’re amenable.

 

[gregorio]

[1] You can shout "bull****" as many times as you like....
[2] But, if you'd spend a little of that effort reading up on current signal processing technology, you would learn that those analysis tools do in fact exist, and that separating information from hoise, even when the noise is at a higher level than the information, is well established technology, as well as the theory that explains why and how to do it, and enables a good programmer to create new analysis tools that do specific things even more accurately.
[3] As a broad generalization, when you want to analyze something, you start by looking at ALL the information you have; you do NOT throw half of it away, while cheerfully exclaiming "I just know there was nothing useful in that half", then declare that anybody who disagrees with that absurd claim must be wrong.

1. But you can't keep spouting BS as many times as you like, this is NOT the "KeithEmo BS" forum, it's the Science Forum!

2. Instead of just more utter BS and using the same tired old audiophile tactic of extreme hypocrisy, why don't you take your own advice? Why don't you spent a little effort reading up on current signal processing? If you did, you would learn that in fact those analysis tools DO NOT exist (that are capable of doing what you're suggesting), that in fact not even the scientific theory exists on which such a tool could be based! Why don't you start with this, the most useful recent scientific paper on the subject I've seen, because it investigates and evaluates the different current approaches to signal extraction. While the science has developed significantly recently, it can only deal with certain specific signals and conditions (isolated signals for example), signals and conditions which are NOT applicable to commercial audio recordings, which are massively more complex. And, it's not just an issue of developing the technology to be better, it's an issue for which there isn't even a practical theory which could achieve what you're suggesting. Quote: "Despite the recent advances in BSS and PAE, the challenges due to the complexity and uncertainty of the sound scenes still remain to be resolved.". The proposed suggestion is that all the information of the recording; mics types, positioning relative to the source, etc., and all the mixing process details be fed into some future processor, so it's got some idea what it's looking for but, none of that information exists for any past or current recording, let alone all of it and in the vast majority of cases it's totally impractical/impossible to log all that information for future recordings. So as far as even the theory is concerned (let alone an actual implementation), we're currently at an impasse.

Furthermore, if you'd spent some time actually using the current signal analysis and processing tools, rather than just reading the marketing, you'd learn what is actually currently possible! De-Noiser technology has been around for decades, the best ones currently are by Cedar and iZotope and they are much better than those of a decade ago. However, they cannot actually De-Noise, that's just marketing, they CANNOT isolate the signal from the noise, typically they can only reduce noise by about 6-8dB before the artefacts become too great BUT even then, it only works that well if you feed it relatively simple, raw (unprocessed), un-mixed channels of sound. As soon as the complexity increases, their effectiveness reduces, and that's what you're talking about, applying these tools not only to processed sound but processed sound that's mixed with many layers of other processed sound. The same situation is true with reverb analysis/removal. I'm sure it works absolutely perfectly if you create the ideal signal+reverb for it but I wouldn't know because I only ever give it real recordings which were NOT specifically designed for it!

3. Huh, are you completely NUTS? You stated: "I would use a high pass filter to separate the ultrasonic content from the "audible music". Then I would boost it a bit to make it easy to work with. Then I would fed it into a DSP engine running appropriate software to analyze it." And now you state: "you start by looking at ALL the information you have; you do NOT throw half of it away," So just to clarify, you're saying that as throwing half the information away is bad, what you would do instead is throw away 99%-100% of it. Good luck with that, knock yourself out! Secondly, what "half" am I throwing out, show me a single commercial recording where half (or for that matter even a tenth) of the information is at >20kHz.

[4] It's pretty obvious, from even a cursory visual obsrvation of the one sample BigShot provided in that link, that those ultrasonic frequencies contain some sort of information... at least in the song he looked at.
[5] (a) If I have an instrument whose primary frequency is at 2 kHz...
(b) - the level and phase relationship of the harmonic at 4 kHz provides information
(c) - and the level and phase relationship of the harmonic at 24 kHz will give me MORE information
[6] I'll gladly stop claiming that such things are possible.... Right after you show me ...

4. Yes, it contains "some sort of information" BUT, WHAT SORT OF INFORMATION? Does it specifically contain acoustic/reflection information because if it doesn't, then any disagreement on how impossible it currently is to isolate acoustic information is completely moot anyway!! How many times?

5. Another absolute beauty, it really is truly impressive! Let look at your three statements and the typical type of fallacy you use to relate them and end up with your utter BS:
a. OK, lets take that example.
b. Yes, it could.
c. Sure ... Providing you ignore all the evidence AND the laws of physics!
Back in the real world:
Statement "a": There are very few instruments which produce a primary (fundamental) frequency as high as 2kHz. In say an orchestra, there's only two; the piccolo and the violin. Still an entirely valid example though.
Statement "b": An instrument producing a 2kHz fundamental will have a 4kHz 2nd harmonic but that harmonic will provide less information than the fundamental (2kHz) frequency because it will be of lower level to start with and will be more prone to absorption.
Statement "c": Now this statement is problematic on several levels! Let's look at the actual evidence, which very fortunately specifically exists for one of the instruments mentioned, the violin. In the James Boyk Paper (1997) he carefully measured and analysed the specifically >20kHz output of a violin. Depending on whether it was played sul-ponticello or double-stopped, as a percentage of the total power the violin produced throughout the spectrum, the >20kHz band accounted for just 0.02% and 0.04% respectively. But wait, it gets even worse (!) because that figure was obtained from close mic'ing the violin. The calculation of air absorption at 100ft distance for a 24kHz harmonic (relative to 2kHz content) is 20.7dB. Admittedly 100ft is further than the typically ideal listening position but still, we've got virtually nothing to start with and have to reduce it by a factor of about 4 times! And if that's not bad enough, these are the figures for the direct sound, what's going to happen with far lower level reflections? They've got much more air to travel through AND they're going to be absorbed by the wall materials! You'd have more luck trying to record a quark farting during a thunderstorm! I've provided the published scientific evidence and applied the laws of physics, which fully supports my assertion that there would be no recordable acoustic information above 20kHz (in fact I highly doubt there'd be anything above 10kHz). Violins is one of the instruments YOU mentioned analysing and even if we take the most optimal close mic'ed figures, you propose to achieve this by "throwing away" 99.96% of the information and analysing the remaining 0.04% for acoustic information which isn't even there! Now, for the umpteenth time, it's well past time for you to PUT UP OR SHUT UP, provide some evidence that there is any recorded acoustic information above 20kHz.

6. How long have you been a member of this sub-forum? In all that time have you never bothered to read the home page or learn anything about science or fallacies? Try clicking the "Burden of Proof" link for a beginner's version! It is unacceptable here to make-up BS and to continue to claim BS until someone proves you wrong, it's up to YOU to substantiate your claim. Despite this, I've provided you with evidence above, so yet again, provide evidence of recorded acoustic information >20kHz, PUT UP or SHUT UP!!

G

 

[KeithEmo]

You've got most of the basic facts more or less right.... but you've sort of missed some of the details and the consclusions.

It's well established that many things produce some output up to and including very high frequencies.
For example, even a relatively clean 1 kHz square wave produces harmonics into the megahertz (theoretically up to infinitely high frequencies).
In fact, many complex waveforms contain harmonics that theoretically extend to infinitely high frequencies.
(Many old style LED displays were chopped using a square wave at a few hundred Hz.... and produced harmjonics high enough to interfere with AM radios.)
And things like a cymbal hit contain at least some components reaching into the very high ultrasonic range.
And that information is PRESENT... whether we humans can hear it or not.
The argument about "whether high-res recordings are audibly different" focuses on whether those sounds may in fact be audible to some people.

HOWEVER, exlcuding for the moment whether anyone can HEAR them or not, those high frequency components can be used to obtain OTHER information.
For example, by analyzing the arrival times of echoes of some of those high frequencies, we may be able to tell how large the studio was, and what it was made of.

When someone hits a cymbal, we can tell what the walls and floor were made of by analyzing the spectrum of the echoes....
For example, concrete floors absorb certain frequencies more thoroughly than others, and wood walls act differently.
So, by comparing the spectrum of the original hit, to the spectrum of the echo, we can tell what the wall was made of by comparing the amounts of various frequencies present in both.
As a simple example, if the original cymbal hit was bright, but the first echo sounded dull, then the wall that first echo bounced off of was probably padded.
And, if that first echo was bright, then that wall was probably very reflective.
(And we can tell how far away the wall was by measuring the delay between the first hit and the echo.)
This gives us INFORMATION about where that cymbal was recorded.

That information may them be useful for something (other than listening to).
Maybe I juts want to know abut the studio.
Oe, maybe, the vocalist sounds as if she was recorded in a different room.
By knowing what both rooms were like, I can add some specific reverb to the vocals, and make them sound like they were recorded in the same room as the cymbals.

And, more to the point of what I was saying....
A modern surround sound processor mught use information like that to learn about the original venue so as to adjust its operation in some fashion.

I pointed out that we already DO have processes that use inaudible information for quite useful purposes.
Click-and-pop reducers use ultrasonic information to tell record clicks from sounds recorded in the music.
The Plangent process uses inaudible high-frequency residual record bias to correct tape flaws.
The ICE optical process uses invisible infrared components to accurately tell the difference between scratches on a photo negative and lines that are part of the actual photo.

The list goes on and on, and I merely suggested that some of the information that is obviously present in those recordings may well prove useful - even in "consumer gear".
(You might be amazed how much computer processing goes into, for example, synthesizing height channels from a two-channel recording.)
Perhaps next week's surround decoder will use that information it figures out about the studio to make more accurate height speaker channels...
If so, then it will work much better with recordings that have retained that information than with those that haven't.
I don't know... and neither can anyone else.

This may be valid data as to instruments and their harmonics: http://www.zytrax.com/tech/audio/audio.html (go to the bottom of the page). I'm not competent to judge it, but I believe it. So the only thing you have up there above 20 khz is percussion harmonics that maybe a very small sliver of the population can hear a small portion of during the early part of their lives, if I am reading and understanding this right.

What do you think? Am I getting this right?

If I understand correctly a person here is saying they measure and then verify distant harmonics from the jazz drum kits above 20 khz in recordings by digitally modifying the pitch down into the audible range and amplifying it greatly. It sounds reasonable to me. The chart would indicate the cymbals and hi-hats can go up to 24 khz in the sixth harmonic. Again, I am not competent to judge the accuracy of this information. But the chart and the reported data seem consistent to me. To me the idea you have expressed of an instrument that plays a fundamental tone of 2 khz producing a 24 khz harmonic seems outlandish. It's just an uninformed guess on my part.

Do you think it's outlandish? Do you have any way to test it? It is you who are making the claim--that's standard operating procedure--to ask the person making the affirmative claim to offer proof. I'm not going into analogies, I'm just asking a dry question.

Can we agree on this--that the frequencies from musical instruments above 20 khz are of no use at all to the home consumer with today's technology? If I am reading things correctly and putting two and two together right, at Bigshot's request I listened to a file of just such information with headphones that are measurably demonstrated to produce the frequencies at least up to 22 khz without attenuation and I heard absolutely nothing at what would be ear-damaging volumes if there were any common audible musical content.

What about the idea that if you could hear these sounds just barely in isolation, they would be masked by anything resembling music. Would you agree with that?

We need to think carefully and organize your thoughts and hit it on the merits, and I think you need to accept that when you have made a claim it's up to you to prove it or else we would err under the circumstances that necessitated the creation of this sub-forum in trusting your bare assertion. We can argue as to who is making the claim as a matter of semantics, but it looks to me like you are making the affirmative claims here. If you think Gregorio is making an affirmative claim as to what can be done with certain information rather than negating your claims, let me know. He may well show you actual proof of the affirmative assertions he is making. I see him as doubting your claims, though. If so, it would be best and standard-issue protocol and rigor if you came forward with actual proof of your assertions. It's not really fair to ask someone to prove that they know or don't know the unknowable. If anything it is at least bordering on tautology that they don't know the unknowable.

Would you agree?

I think you know more than I do. Help me out here.

Honestly, I hope you will provide an informative response that I can enjoy as a learning experience and a good read. That is my hope.

(Edited several times for better clarity.)

 

[KeithEmo]

Yets, amazingly enough, over thirty years ago, I had a burglar alarm that could, with excellent accuracy, tell the difference between a breaking window and a RECORDING of a breaking window... by analyzing those totlaly useless ultrasonic harmonics of the sound. And it didn't even have a DSP in it. (Shattering glass seems to make a lot of easily identifiable sounds above 20 kHz.)

Actually, what I was saying was that you look at ALL the parts.... sometimes that's easier if you look at them all together... and sometimes you pick them apart and look at the individual pieces separately... often you do both and combine the information you get from each.

1. But you can't keep spouting BS as many times as you like, this is NOT the "KeithEmo BS" forum, it's the Science Forum!

2. Instead of just more utter BS and using the same tired old audiophile tactic of extreme hypocrisy, why don't you take your own advice? Why don't you spent a little effort reading up on current signal processing? If you did, you would learn that in fact those analysis tools DO NOT exist (that are capable of doing what you're suggesting), that in fact not even the scientific theory exists on which such a tool could be based! Why don't you start with this, the most useful recent scientific paper on the subject I've seen, because it investigates and evaluates the different current approaches to signal extraction. While the science has developed significantly recently, it can only deal with certain specific signals and conditions (isolated signals for example), signals and conditions which are NOT applicable to commercial audio recordings, which are massively more complex. And, it's not just an issue of developing the technology to be better, it's an issue for which there isn't even a practical theory which could achieve what you're suggesting. Quote: "Despite the recent advances in BSS and PAE, the challenges due to the complexity and uncertainty of the sound scenes still remain to be resolved.". The proposed suggestion is that all the information of the recording; mics types, positioning relative to the source, etc., and all the mixing process details be fed into some future processor, so it's got some idea what it's looking for but, none of that information exists for any past or current recording, let alone all of it and in the vast majority of cases it's totally impractical/impossible to log all that information for future recordings. So as far as even the theory is concerned (let alone an actual implementation), we're currently at an impasse.

Furthermore, if you'd spent some time actually using the current signal analysis and processing tools, rather than just reading the marketing, you'd learn what is actually currently possible! De-Noiser technology has been around for decades, the best ones currently are by Cedar and iZotope and they are much better than those of a decade ago. However, they cannot actually De-Noise, that's just marketing, they CANNOT isolate the signal from the noise, typically they can only reduce noise by about 6-8dB before the artefacts become too great BUT even then, it only works that well if you feed it relatively simple, raw (unprocessed), un-mixed channels of sound. As soon as the complexity increases, their effectiveness reduces, and that's what you're talking about, applying these tools not only to processed sound but processed sound that's mixed with many layers of other processed sound. The same situation is true with reverb analysis/removal. I'm sure it works absolutely perfectly if you create the ideal signal+reverb for it but I wouldn't know because I only ever give it real recordings which were NOT specifically designed for it!

3. Huh, are you completely NUTS? You stated: "I would use a high pass filter to separate the ultrasonic content from the "audible music". Then I would boost it a bit to make it easy to work with. Then I would fed it into a DSP engine running appropriate software to analyze it." And now you state: "you start by looking at ALL the information you have; you do NOT throw half of it away," So just to clarify, you're saying that as throwing half the information away is bad, what you would do instead is throw away 99%-100% of it. Good luck with that, knock yourself out! Secondly, what "half" am I throwing out, show me a single commercial recording where half (or for that matter even a tenth) of the information is at >20kHz.

4. Yes, it contains "some sort of information" BUT, WHAT SORT OF INFORMATION? Does it specifically contain acoustic/reflection information because if it doesn't, then any disagreement on how impossible it currently is to isolate acoustic information is completely moot anyway!! How many times?

5. Another absolute beauty, it really is truly impressive! Let look at your three statements and the typical type of fallacy you use to relate them and end up with your utter BS:
a. OK, lets take that example.
b. Yes, it could.
c. Sure ... Providing you ignore all the evidence AND the laws of physics!
Back in the real world:
Statement "a": There are very few instruments which produce a primary (fundamental) frequency as high as 2kHz. In say an orchestra, there's only two; the piccolo and the violin. Still an entirely valid example though.
Statement "b": An instrument producing a 2kHz fundamental will have a 4kHz 2nd harmonic but that harmonic will provide less information than the fundamental (2kHz) frequency because it will be of lower level to start with and will be more prone to absorption.
Statement "c": Now this statement is problematic on several levels! Let's look at the actual evidence, which very fortunately specifically exists for one of the instruments mentioned, the violin. In the James Boyk Paper (1997) he carefully measured and analysed the specifically >20kHz output of a violin. Depending on whether it was played sul-ponticello or double-stopped, as a percentage of the total power the violin produced throughout the spectrum, the >20kHz band accounted for just 0.02% and 0.04% respectively. But wait, it gets even worse (!) because that figure was obtained from close mic'ing the violin. The calculation of air absorption at 100ft distance for a 24kHz harmonic (relative to 2kHz content) is 20.7dB. Admittedly 100ft is further than the typically ideal listening position but still, we've got virtually nothing to start with and have to reduce it by a factor of about 4 times! And if that's not bad enough, these are the figures for the direct sound, what's going to happen with far lower level reflections? They've got much more air to travel through AND they're going to be absorbed by the wall materials! You'd have more luck trying to record a quark farting during a thunderstorm! I've provided the published scientific evidence and applied the laws of physics, which fully supports my assertion that there would be no recordable acoustic information above 20kHz (in fact I highly doubt there'd be anything above 10kHz). Violins is one of the instruments YOU mentioned analysing and even if we take the most optimal close mic'ed figures, you propose to achieve this by "throwing away" 99.96% of the information and analysing the remaining 0.04% for acoustic information which isn't even there! Now, for the umpteenth time, it's well past time for you to PUT UP OR SHUT UP, provide some evidence that there is any recorded acoustic information above 20kHz.

6. How long have you been a member of this sub-forum? In all that time have you never bothered to read the home page or learn anything about science or fallacies? Try clicking the "Burden of Proof" link for a beginner's version! It is unacceptable here to make-up BS and to continue to claim BS until someone proves you wrong, it's up to YOU to substantiate your claim. Despite this, I've provided you with evidence above, so yet again, provide evidence of recorded acoustic information >20kHz, PUT UP or SHUT UP!!

G

 

[gregorio]

You've got most of the basic facts more or less right.... but you've sort of missed some of the details and the consclusions.

So that's a "no" then, you can't provide a single shred of evidence to support your claim that there is any acoustic information above 20kHz. All you can do is just repeat exactly the same BS, even though evidence supporting it's refutation has been provided. Therefore, not only do I have every right to call you a bullsh*ter, but in this sub-forum it's a duty! Now all you have to do is fulfil your promise "I'll gladly stop claiming that such things are possible...." but it doesn't appear that you're honest enough even to do that!!!

G

 

[KeithEmo]

I'm inclined to agree there....

However, to use your analogy....
I'm sure there are a few people who insist that the undulations make them seasick... while they don't mind the potholes...
And perhaps even a few cars with soft suspension that bounce madly when they hit undulations of a certain size...
(I once owned a Dodge Diplomat that had very soft suspension. It cruised right over potholes, but sometimes bounced alarmingly if the road was unlevel.)
And, regardless of their relative importance, at least in principle, a perfectly level flat road would technically be better than one with undulations or potholes....

And that last point is the relevant one.
There are two entirely different questions there.
1) Does "the MQA process" do what they claim and make a TECHNICAL improvement in the quality of the recording?
2) Can you, or anyone, hear that difference, and how many people care about it (whether they can hear it or not)?

In point of fact, many MQA files do sound substantially different than the originals (and many do not)...
However, many of them are also subject to "other remastering", and details are rarely provided...
This makes it difficult to determine exactly how they were changed along the way...

Dolby Labs also includes options in their current top-line encoder to address and correct "ADC issues".

So, whether you or I agree or not, "credible people seem to believe there's something to this and are working on it".
And, obviously, folks like the Navy and the Air Force continue to do research in "extracting information from noise" - for use with RADAR, sonar, and other similar technologies.
And, at least sometimes, previously "useless" information turns out to be useful after all.

Yes I understand that, I was just pointing out there are more flaws in playback from the analog source (ie from the tape machine converting the magnetic layer of the tape to an electrical signal) than in the ADC conversion.

Correcting 'flaws' in ADC conversion while ignoring the flaws from electro/magnetic/mechanical analog sources is like leveling out a slight undulation in the road while ignoring the pot holes.

 

[Phronesis]

So that's a "no" then, you can't provide a single shred of evidence to support your claim that there is any acoustic information above 20kHz. All you can do is just repeat exactly the same BS, even though evidence supporting it's refutation has been provided. Therefore, not only do I have every right to call you a bullsh*ter, but in this sub-forum it's a duty! Now all you have to do is fulfil your promise "I'll gladly stop claiming that such things are possible...." but it doesn't appear that you're honest enough even to do that!!!

G

@KeithEmo, I encourage you not to reply to the quoted post. You deserve better than to be repeatedly personally insulted. I've really appreciated your substantive and measured posts in this thread, and would like to see them continue.

 

[KeithEmo]

Hmmmm.....

Let's see.......

That burglar alarm I had used acoustic information above 20 khz to tell the difference between a real break-in and a TV show.
And the Plangent process uses very high frequency ultrasonic information to correct issues with old master tapes.
And, let's not leave out our little furry friends, the bats, who use ultrasonic acoustic information to navigate.
(And BigShot provided examples of actual non-random ultrasonic information present in actual high-resolution recordings.)

That's three examples of technologies that use "USEFUL acoustic information above 20 kHz"....
And one demonstration that it really is present in at least some high-res recordings....
How many examples do you need?
Or are you suggesting that I just made up those examples....?

Incidentally, here's an interesting technical paper about "determining information about a room from ultrasonic echoes".
This particular example considers using a generated signal rather than one that is already present (lie RADAR or SONAR).
That makes the job of detailed analysis simpler....
However, it addresses various issues about "how to extract useful information from a jumble of echoes".
https://www.researchgate.net/public...stics_Simulator_for_Ultrasonic_Robot_Location

And, just for fun, if I happen to listen to a high-res recording of Tommy, I'll finally get to know about that scene where the mirror gets smashed.
(Did the Foley guys really smash a mirror in the studio - or did they smash it outside and record it on a separate track - or did they use a tape recorded sample of breaking glass?)

So that's a "no" then, you can't provide a single shred of evidence to support your claim that there is any acoustic information above 20kHz. All you can do is just repeat exactly the same BS, even though evidence supporting it's refutation has been provided. Therefore, not only do I have every right to call you a bullsh*ter, but in this sub-forum it's a duty! Now all you have to do is fulfil your promise "I'll gladly stop claiming that such things are possible...." but it doesn't appear that you're honest enough even to do that!!!

G

 

[KeithEmo]

Thank you... and you're quite right...
I think I've provided more than enough examples to prove my point to anyone who is really interested...
It's time to move on.

@KeithEmo, I encourage you not to reply to the quoted post. You deserve better than to be repeatedly personally insulted. I've really appreciated your substantive and measured posts in this thread, and would like to see them continue.

 

[Zapp_Fan]

Is it really controversial that hi-res recordings could contain acoustic information in the ultrasonic band?

I mean, in the other thread on HD tracks and ultrasonics, it's pretty easy to hear in those recordings (after pitching down 90%) that there's actual ultrasonic stuff that obviously corresponds to the music.

To my ear, it's either ultrasonic noise being modulated by the audio band, or it's actually from the instruments themselves. (It certainly doesn't sound tonal.) Anyway, assuming it's the latter, that would certainly (technically) count as acoustic information in the ultrasonic band.

(Whether it's of any practical use is a question for researchers, I suppose.)

Do we happen to know for a fact that it would be the former?

@KeithEmo - I personally get the drift of your posts and don't think you're completely off base on anything. I think two things work against the quality of the discussion - one is that you are reluctant to speak in absolute terms (as am I), and the other is that your posts tend to be of substantive length. I think by making several points in one post, it reduces the likelihood that they are all well-understood - it's clear that the pace of posting ITT is extreme, especially considering the word count... I don't see that the typical M.O. is to sit and digest a long post before responding.

It seems that sometimes, taking the stance of "I can't rule it out absolutely" is interpreted as positive support for the position, but I don't really see it that way.

I find it's safer to be brief and try to address a singular topic.

 

[gregorio]

To my ear, it's either ultrasonic noise being modulated by the audio band, or it's actually from the instruments themselves. (It certainly doesn't sound tonal.) Anyway, assuming it's the latter, that would certainly (technically) count as acoustic information in the ultrasonic band.

No, that would count as direct signal information, not acoustic information, information about the room acoustics in which that instrument was recorded.

Let's see.......
[1a] That burglar alarm I had used acoustic information above 20 khz to tell the difference between a real break-in and a TV show.
[1b] And the Plangent process uses very high frequency ultrasonic information to correct issues with old master tapes.
[1c] And, let's not leave out our little furry friends, the bats, who use ultrasonic acoustic information to navigate.
[1d] (And BigShot provided examples of actual non-random ultrasonic information present in actual high-resolution recordings.)
[2] How many examples do you need?
[3] Incidentally, here's an interesting technical paper about "determining information about a room from ultrasonic echoes". This particular example considers using a generated signal rather than one that is already present (lie RADAR or SONAR).

1. Let's see indeed.
1a. Don't you know the difference between evidence and anecdote? How about what the word "analogy" means? If you can provide some evidence that your burglar alarm was using ultrasonic information to work out the acoustic properties of the room the TV or burglar was in, then we'd have an analogy that was actually analogous, instead of your REPEATED tactic of an analogy that isn't an analogy!
1b. Again, what has that got to do with acoustic information?
1c. And all your music recordings contain bat call/echolocation signals do they? Please give me just one example of a music album that contains 120dB of ultrasonic bat signals/reflections.
1d. Great, then what's stopping you pointing out the acoustic information within that ultrasonic information?

2. ONLY ONE ... WHERE IS IT? After you demonstrate that ultrasonic acoustic information exists on at least one commercial audio recording, ONLY THEN we can talk about it's possible extraction, analysis and how it *might* be useful with the fantasy/futuristic surround sound system you're suggesting. How many times?

3. How many music albums do you have that contain RADAR reflections of the recording venue/s? Just one example will do.

[1] You deserve better than to be repeatedly personally insulted.
[2] I've really appreciated your substantive and measured posts in this thread, and would like to see them continue.

1. No, we deserve better than to have this forum deliberately and repeatedly insulted! He has no excuse, he's not a newbie here.

2. If you "really appreciate" misrepresented fact and made-up BS to fulfil KeithEmo's agenda, and would like to see it continue, that's entirely up to you, just not here, this is the Sound Science forum!! If this is a democracy and everyone wants BS rather than facts/science, no problem. Just rename the forum "KeithEmo's BS" forum and everyone will be happy (except those interested in the facts/science).

G

 

[Zapp_Fan]

No, that would count as direct signal information, not acoustic information, information about the room acoustics in which that instrument was recorded.

Oh right, good point.

Still I think we might be overestimating how much ultrasonic content gets absorbed in free air / reflections. It's a lot but it's not instantly extinguished either.

Attenuation in free air is only roughly 1-5dB/m at "lower" frequencies, (under 100khz or whatever) reflections are expected to be much more attenuated than normal audio, but Keith's point about sonar being a useful technology indoors does prove that reflected ultrasound is reliably detectable in normal spaces. Not all recording venues completely lack surfaces that might return some reasonable-amplitude ultrasound to the mic's position.

If the wall is 3 meters from the musician, we might get (say) 6dB attenuation from the air plus (say conservatively) another 20dB from the reflection, for all I know at -26dB the 24khz crap coming off a cymbal is still an intelligible signal for some arbitrary purpose.

To put it another way, if (for some strange reason) you tasked me with making sure that no useful amount of reflected ultrasound reached a mic in a recording session, I couldn't just assume that the problem would take care of itself.

 

[Phronesis]

Here's a thought: intelligent, informed, and truth-seeking people may not always agree on what's true or false, possible or not possible. A corollary is that intelligent, informed, and truth-seeking people can sometimes be wrong without knowing they're wrong, despite believing that they're right. That's where humility comes into play, and people with humility are willing to say things like "I'm not sure," "I could be wrong," "I guess it's possible," "this is what I think, but I can't be sure of it," etc. Research has also shown that confidence in a belief isn't generally a good indicator of how accurate the belief is. I believe most scientists would agree with all of this, and it's worthwhile to do some study of the history of science to see how prevailing ideas have changed over time, sometimes very dramatically (paradigm shifts, scientific revolutions, etc.).

 

[gregorio]

Here's a thought: intelligent, informed, and truth-seeking people may not always agree on what's true or false, possible or not possible. A corollary is that intelligent, informed, and truth-seeking people can sometimes be wrong without knowing they're wrong, despite believing that they're right.

All true. And the solution couldn't be more simple, for KeithEmo to support his claims with some evidence, or are you advocating that intelligent, informed and truth-seeking people should accept any old made-up unsubstantiated theory or BS?

G

 

[KeithEmo]

If I actually do ever suspect that there were bats in that studio, these guys seem to have the equipment that will enable me to identify the species...
http://www.latimes.com/projects/bat-sounds-library/
(of course that will only work if the recording hasn't been bandwidth limited).

I wonder if they have an album....
And, yes, the echoes of bat signals do contain acoustic information...
And bats do use them to collect data about things like... where the walls are... and what they're made of.
And, yes, they seem to be somewhat better at analyzing that data than we are... at least for now.

No.... I'm really done being baited into responding this time

No, that would count as direct signal information, not acoustic information, information about the room acoustics in which that instrument was recorded.



1. Let's see indeed.
1a. Don't you know the difference between evidence and anecdote? How about what the word "analogy" means? If you can provide some evidence that your burglar alarm was using ultrasonic information to work out the acoustic properties of the room the TV or burglar was in, then we'd have an analogy that was actually analogous, instead of your REPEATED tactic of an analogy that isn't an analogy!
1b. Again, what has that got to do with acoustic information?
1c. And all your music recordings contain bat call/echolocation signals do they? Please give me just one example of a music album that contains 120dB of ultrasonic bat signals/reflections.
1d. Great, then what's stopping you pointing out the acoustic information within that ultrasonic information?

2. ONLY ONE ... WHERE IS IT? After you demonstrate that ultrasonic acoustic information exists on at least one commercial audio recording, ONLY THEN we can talk about it's possible extraction, analysis and how it *might* be useful with the fantasy/futuristic surround sound system you're suggesting. How many times?

3. How many music albums do you have that contain RADAR reflections of the recording venue/s? Just one example will do.



1. No, we deserve better than to have this forum deliberately and repeatedly insulted! He has no excuse, he's not a newbie here.

2. If you "really appreciate" misrepresented fact and made-up BS to fulfil KeithEmo's agenda, and would like to see it continue, that's entirely up to you, just not here, this is the Sound Science forum!! If this is a democracy and everyone wants BS rather than facts/science, no problem. Just rename the forum "KeithEmo's BS" forum and everyone will be happy (except those interested in the facts/science).

G