Wideband Speakers

[avole]

Old saying: Don't argue with fools or madmen.

Cheers,
Alec

Can't agree more. I suggest leaving this topic to desktop alone now.

Desktop reminds me of a charming old gentlmen I met once while on a Nile cruise. He had once been something high up in the Carter administration, and had been studying Ancient Egypt exhaustively since. I knew little of the subject, I'm afraid to admit, so I listened with great interest to his comment, and the stories he told.

This was a guided tour, and the guide, a thoroughly knowledgable chap, would give a brief lecture followed by a question and answer session. My friend was prominent in the latter, and it became obvious to me that he had a pet theory of the timing of the classic period in Egyptian history, and the events that his theory showed in a certain light were not at all in accord with the explanation the tour guide was giving.

We talked about this over several evenings and glasses of red, until the tour finished or not. The ex-administrator had indeed formulated his own theory, drawn from numerous sources - he was a thoroughly scholarly gent. It was clear, too, that if he were right, the Egyptian historians had a lot of thinking to do. There was a problem, though, which I brought on early on, that of carbon dating.

He was well aware of this, and went through all the known problems of carbon dating, including it's famous inaccuracy. However, and I'll freely admit to not being an expert, it did mean that if the carbon dating used by archaeologists were correct, then his theories were questionable, if not in incorrect.

Now, I do not know to this day whether my friend's theories had substance or not, although they made for enjoyable evenings as the three of us (the tour guide had become interested and joined our little group) debated all manner of topics as the Nile floated gently by. I did and do think, however, that the dating question needed resolution, and that all the evidence was on the side of conventional wisdom. I feel such is the case now. Desktop, who I picture in the white safari suit of my friend, Nikon round his neck, leaning forward over the deck rails to better devour the sights and sounds, needs to prove that humans can hear above the accepted norms, that this ability can be taught, that age apparently causes less deterioration if you're a super listener, and lastly that having 'golden ears' is directly related to the ability to hear above the normal frequency range of human hearing. Until he does, I'm afraid the verdict is always going to be less than positive.

[desktop]

to Alec124c41,
I prefer to stick to analogies that involve some form of sensory physics, instead of bring up all sorts of other kinds of stories. So here is an audio story.

I get to be the one who helps all my extended family members with their sound systems. My brother-in-law uses a generic DD TT that is about 30 years old. That TT was worth what he paid for it for sure (about US$59). He disliked the sound of a variety of his phone cartridges from AT and Orto so for Christmas I installed a 30 year old Stanton 681EE in it. He liked it from the first instant he heard it.

But I didn't like the sound at all. I took the cartridge home and tried it and it sounded great (he had had an Empire 2000ZE first but because of the odd grounding strap situation on the Empire one channel was silent, thus the Stanton). I looked everywhere in the connections thinking the problem was strictly mechanical. Nothing improved what I thought was an indistinct midrange. But he loved the tighter bass and clearer high end he was getting, so I left it.

At a recent get-together, I was watching the neon speed display and I swore I could see it creeping faster and then slowing down, quite a few times. I tried another record and before even setting the needle down, I could see speeding up and slowing down registering on the 60Hz neon speed display. With the needle down on the record the speed variation was worse.

I know that wow and flutter is what is making his sound irritating to me. He should grease/oil the bearing but that is often not worth the money on a DD TT. If his turntable finally smokes up, I'll give him one of many I have stored in my barn in super large freezer baggies. But it was only when I pointed out the pronounced speed variations showing on the neon speed display, while my brother-in-law was listening to one of his fave records, by 10,000 Maniacs, that he could then identify what was happening to the sound, as the strobe display varied faster and slower. Until then he didn't hear this problem.

This is about the millionth time that I have said to someone (about audio), "what's that? To which 99.9% of the time the responder listens briefly and says, "what's what". I'm much better with sounds that shouldn't be there, as opposed to sounds that are missing. But the degree to which we are sound-sensitive probably varies.

In any case I asked a dissenter in the CD vs SACD AES test about it and we realized 2 things. Hiring successful AES people to do audio work isn't always because they have good ears let alone Golden Ears. Sometimes the people who are reknown within the AES are great managers or great at working with other artistic talents. The lack of standards in the test of SACD vs CD sound, and no way to know the hearing acuity of the listeners is a real problem.

But going back to the test to see who could sense high frequencies in sound better than anyone else the AES could find, when the first discussion about CD standards was brewing, there have never been any arguments about the validity and value of that test. That test was designed to test listeers' ability to sense ultra-high frequencies on a "are they there" or "aren't they there" basis.

Discovering a Danish engineer, age 22, who was correct in sensing the ultra-highs needed to score a consistent 90% right score on the test at 80KHz, is kind of cool, I think, but the test showed that dozens of AES engineers can sense the presence of high frequency energy above 40KHz (but sadly not me, even though I was in my late 30s). That test was actually trying to determine whether AES audio people could sense ultra-high frequency energy.

The test equipment had been measured, the program material was measured, the lo pass filters had been measured, and the ability to sense ultra-high frequencies or not, was the variable or unknown. The "decision" is who can sense enough of the high frequency energy, in a double blind test, to score a convincingly high number of correct answers at various levels of cutoff.

In the recent AES test the listeners' hearing is unknown, as is the loudspeaker's ability to produce clean output up to 40KHz. Since those are the real factors involved in the "decision" here, any decision is most likely meaningless. In fact either one of those unknowns can make the results useless.

It really isn't that hard to go listen to a loudspeaker with extended high frequency response. Then you would know for yourselves, whether extended high frequency output is meaningful to you or not. Better to check things to learn for yourself, than to be put off by people who haven't heard these products.

[Ldg]

It really isn't that hard to go listen to a loudspeaker with extended high frequency response. Then you would know for yourselves, whether extended high frequency output is meaningful to you or not.

Yes, but you may still be none the wiser as to whether any perception is real or imagined/phantom. As with so many such inexplicable audiophile things, it seems.

Look, there is no useful content in vinyl at these frequencies. Unless you count in CD4 carrier/sidebands ? That would be like tinnitus Why do you think they put CD4 et al carriers/sidebands there ?

Coincidentally, today I installed a switchable 28kHz low pass filter in a phono preamp. Because I deliberately wanted associated attenuation artifacts that extend below 20kHz to address another issue. This is barely audible to me, but i believe i might pass a blind test. Filter at 28kHz can have audible artifacts that extend into normal audioband. But there's no way I can hear/perceive/smell a 20kHz sine tone, unless there's some IMD going on (as can be the case). One has to be very careful about interpretation. I can detect 28kHz filter in/out because of sub 20kHz audioband filter artifacts. But can't hear 20kHz tones.

[dlaloum]

Question is: what kind of test could be devised that seperates ultraHF sound from its IM's?

All of these tests have demonstrated that the hearers in these specific situations could sense the presence or absence of the UHF - BUT - there has been no investigation of how this was achieved, and whether they were sensing the sound itself, or identifying the intermodulations that are under 20kHz.

If it is the latter - then in an audio reproduction sense it should be considered an undesirable distortion, as the desirable UHF would already have interacted at recording time and that interaction would be on the recording.


I don't believe any of these tests have found a way around this quandary...

bye for now
David

[Rap]

Question is: what kind of test could be devised that seperates ultraHF sound from its IM's?

All of these tests have demonstrated that the hearers in these specific situations could sense the presence or absence of the UHF - BUT - there has been no investigation of how this was achieved, and whether they were sensing the sound itself, or identifying the intermodulations that are under 20kHz.

If it is the latter - then in an audio reproduction sense it should be considered an undesirable distortion, as the desirable UHF would already have interacted at recording time and that interaction would be on the recording.


I don't believe any of these tests have found a way around this quandary...

bye for now
David

Good point David, but it suggests that the recording mike/equipment ,what have you, records sound in the same way the ear/brain hears and filters distortion.

[dlaloum]

Question is: what kind of test could be devised that seperates ultraHF sound from its IM's?

All of these tests have demonstrated that the hearers in these specific situations could sense the presence or absence of the UHF - BUT - there has been no investigation of how this was achieved, and whether they were sensing the sound itself, or identifying the intermodulations that are under 20kHz.

If it is the latter - then in an audio reproduction sense it should be considered an undesirable distortion, as the desirable UHF would already have interacted at recording time and that interaction would be on the recording.


I don't believe any of these tests have found a way around this quandary...

bye for now
David

Good point David, but it suggests that the recording mike/equipment ,what have you, records sound in the same way the ear/brain hears and filters distortion.

I am assuming that the recording contains a correct analog of the sounds present at the recording venue. (regardless of equipment/method) - and yes without a doubt that can be a constraint as well...

But whatever analog of the sound wave(s) is used to store the recording, it still will not record the same way our ear/brain hears and filters distortion - the mechanisms are just way too different.

All we can do is record as wideband as possible with as much precision as we can devise/measure... and hope that it meets the (only partly understood) requirements of our ears!

[Rap]

All we can do is record as wideband as possible with as much precision as we can devise/measure... and hope that it meets the (only partly understood) requirements of our ears!

Yes, your right ofcause, it's just that I've been reading Thorsen Loesch's thoughts on SET'S and he mentions some interesting research by a Patterson in 1969 about "Ear-congruent Distortion" and subsequent brain filtering of said distortions. :arrow: It might explain some of the discrepencies of what we measure as to what we hear?

[avole]

Question is: what kind of test could be devised that seperates ultraHF sound from its IM's?

All of these tests have demonstrated that the hearers in these specific situations could sense the presence or absence of the UHF - BUT - there has been no investigation of how this was achieved, and whether they were sensing the sound itself, or identifying the intermodulations that are under 20kHz.

If it is the latter - then in an audio reproduction sense it should be considered an undesirable distortion, as the desirable UHF would already have interacted at recording time and that interaction would be on the recording.


I don't believe any of these tests have found a way around this quandary...

bye for now
David

Since you seem a sensible person, I'll ask you, David.

Could you please provide references to all these tests, David. There are plenty of hearing tests you can download that prove otherwise, even the mosquito ringtone.

Also please provide proof that sounds above 20khz impact the sound you can hear below. An explanation of how would also be useful. I'd also suggest checking reputably sources, such as universities and government test laboratories, if possible.

Thanks.

P.S. Research into the function and limitations of the middle ear explains why you cannot hear above 20khz, it is the limit for us humans.

[dlaloum]

Hi Avole,

1) The tests I am referring to are the AES tests referred to by desktop (presumably reports are available from the AES for the standard fees..)

2) Actually devising a test that meets these requirements is extremely difficult - takes a LOT of effort..
Speakers need to be set up in an anechoic chamber, the chamber needs to be tested to ensure that all reflections are absorbed at all frequencies
The speakers/setup need to be tested for linearity at all frequencies up to the test limit, and need to also meet other audiophile test criteria (transient response, phase response, etc....)

Obviously the microphones used for this testing need to somehow be tested themselves...

3) Showing that any tone can affect any other tone is simply a matter of physics... I suggest http://en.wikipedia.org/wiki/Intermodulation as an initial reading point. (particularly the section on passive IM and IM in audio applications)

4) Intermodulation does not require that we be able to hear the fundamental tone - it only requires that we be able to sense (given the thrust of the discussion, hearing might be a somewhat limited term) a change.... And if the products of the intermodulation are distortions residing within the 20-20kHz range then there is a high likelihood that we can indeed hear them.

5) Of particular interest is the subsequent question (with reference to Rap's posting...) - which is how does the brain then interpret the additional signals?
Is the additional sense of space and air frequently provided by cartridges with extended phase linear response, due to the high frequencies reproduced (albeit at low levels) - or due to intermodulations of these signals resulting in sounds within the audio range that our brain automatically interprets as higher frequencies... ie are we wired to recognise higher frequencies by their lower frequency IM products?
And this being a very much wired in brain response, may be something that is learnt at very very early age (before 3years) - after which you either have it or not. The sight and hearing processing centres get "programmed" very early on - if they were not programmed at these early stages - it cannot be remedied later...
Which in turn would beg the question.... What early life influences would help a baby to develop "Golden Ears"?
(And yes, I tend strongly towards nurture rather than nature in that specific argument...)

Avole, I agree in questioning the audibility of material over 20kHz.... but if credible sources respond by saying that some proportion (even if it is a small %) of the population can in fact sense something happening beyond 20kHz, then my question is why and how.
The crux of the matter from your perspective, appears to be the credibility of the sources - in which case might I suggest that you look into finding the original AES material desktop mentioned.
Desktop's CV does entitle him to at least a modicum of credibility in this environment - and if you wish to question his substantially supported opinions, I would think the onus would be on you to research the material, and then come back with relevant counter arguments.

(Mate, you ain't got the troops for this battle.... go find yourself some decent cavalry then you might have a chance of outflanking him... oops .... sorry, wrong forum... I always enjoyed military strategy....)

bye for now

David

[avole]

Of course, another approach is to record a single piano note, middle C, which comes in at 261.626Hz on a wide frequency recorder, then play it back in random sequence with filters applied at 20khz, 15khz and 10khz to a test group of, say, 10000 young people . Blind testing obviously.

If the results show that the test group could not pick the difference, then that suggests frequencies within the audible spectrum but above the natural frequency of a note have no impact on our hearing of that note, then that implies frequencies above 20khz have no impact either.

[dlaloum]

The test setup would be just as critical... and the high frequency content of that chosen instrument would be more limited...

A better choice would be a marimba or vibraphone.... with inherent high levels of HF content.

[avole]

Hi Avole,

1) The tests I am referring to are the AES tests referred to by desktop (presumably reports are available from the AES for the standard fees..)

2) Actually devising a test that meets these requirements is extremely difficult - takes a LOT of effort..
Speakers need to be set up in an anechoic chamber, the chamber needs to be tested to ensure that all reflections are absorbed at all frequencies
The speakers/setup need to be tested for linearity at all frequencies up to the test limit, and need to also meet other audiophile test criteria (transient response, phase response, etc....)

Obviously the microphones used for this testing need to somehow be tested themselves...

3) Showing that any tone can affect any other tone is simply a matter of physics... I suggest http://en.wikipedia.org/wiki/Intermodulation as an initial reading point. (particularly the section on passive IM and IM in audio applications)

4) Intermodulation does not require that we be able to hear the fundamental tone - it only requires that we be able to sense (given the thrust of the discussion, hearing might be a somewhat limited term) a change.... And if the products of the intermodulation are distortions residing within the 20-20kHz range then there is a high likelihood that we can indeed hear them.

5) Of particular interest is the subsequent question (with reference to Rap's posting...) - which is how does the brain then interpret the additional signals?
Is the additional sense of space and air frequently provided by cartridges with extended phase linear response, due to the high frequencies reproduced (albeit at low levels) - or due to intermodulations of these signals resulting in sounds within the audio range that our brain automatically interprets as higher frequencies... ie are we wired to recognise higher frequencies by their lower frequency IM products?
And this being a very much wired in brain response, may be something that is learnt at very very early age (before 3years) - after which you either have it or not. The sight and hearing processing centres get "programmed" very early on - if they were not programmed at these early stages - it cannot be remedied later...
Which in turn would beg the question.... What early life influences would help a baby to develop "Golden Ears"?
(And yes, I tend strongly towards nurture rather than nature in that specific argument...)

Avole, I agree in questioning the audibility of material over 20kHz.... but if credible sources respond by saying that some proportion (even if it is a small %) of the population can in fact sense something happening beyond 20kHz, then my question is why and how.
The crux of the matter from your perspective, appears to be the credibility of the sources - in which case might I suggest that you look into finding the original AES material desktop mentioned.
Desktop's CV does entitle him to at least a modicum of credibility in this environment - and if you wish to question his substantially supported opinions, I would think the onus would be on you to research the material, and then come back with relevant counter arguments.

(Mate, you ain't got the troops for this battle.... go find yourself some decent cavalry then you might have a chance of outflanking him... oops .... sorry, wrong forum... I always enjoyed military strategy....)

bye for now

David

Er, no, actually I have the scientific community on my side, and you should see the size of their chargers!

As you'd be well aware, one set of tests, particularly using methodology that is questionable, is not good proof, scientific or otherwise. As the vast majority of evidence suggests otherwise, it is up to the AES, as represented by the honourable desktop, to supply the proof before any investigation takes place.

Unfortunately, when questioned said person has replied with assertions that are a long way from any kind of proof, scientific or otherwise. The problem for him and the AES is that hearing tests are easy to perform, readily available and indicate that 20khz is the cut off point for a young adult at the peak of his or her hearing abilities. I note that the honourable D hasn't mentioned what his hearing is according to standard tests, which is a strange omission, since he has to prove that those tests are flawed.

As it stands there is zero proof that sounds above 20khz have any impact on sounds below. All that exists, at the moment, is merespeculation, and that doesn't merit serious examination until one of the speculators can prove otherwise.

Make no mistake, the onus is entirely on the honourable D here, since it is he who is trying to turn science on its head, and so far he has failed entirely to do more than bang on about one series of tests and his mates.

Don't get fooled by the pseudoscience, not that there has even been much of that here, nor the constant repetition of the same points, but note instead the failure to answer direct questions, and the deliberate obfuscations.

The emperor's lack of clothes is becoming obvious.

[dlaloum]

I always preferred the empresses new clothes....

[avole]

The test setup would be just as critical... and the high frequency content of that chosen instrument would be more limited...

A better choice would be a marimba or vibraphone.... with inherent high levels of HF content.

I think you've missed the point a little. The point is to demonstrate that the frequencies above, or below if you wish, a note have no impact on its sound, from which you can extrapolate the same occurs throughout the spectrum. Therefore, you choose a note where this is measurable and falls easily within the human frequency range. You do not want one that is too high since your filters would then be above 20khz, outside the limit of human hearing, and therefore would provide no evidence.