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Quote:
Originally Posted by RWetmore /forum/post/16302734


There are still a few labels producing extremely high quality recordings. 2L is the first that comes to mind, but there are others.


Also, according to 2L's founder, their microphones have captured sounds up to 60khz in orchestral recordings (Mozart violin concertos specifically).


I don't doubt that, espcially with close micing. Of course it seems like he tried to play you for a newbie by not citing a +/- dB spec. Without a +/- dB spec he could be talking about a signal that is > 100 dB down, which is never audible.


One lesser-known facts is that high frequency sounds are very rapdily attenuated over realistic distances.


According to http://www.sengpielaudio.com/calculator-air.htm


A 60 KHz tone loses 2.3 dB per meter at 25 deg C and 50% RH.


For grins estimate the distance from the first violin to your favorite seat - I'll bet its over 20 meters. That give over 100:1 loss!
 

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Quote:
Originally Posted by Chu Gai /forum/post/16302155


If you want a medium that goes beyond 22K then you also want microphones, and every last piece of recording and mixing equipment in the entire chain to do likewise. And you want it certified by some independent agency. But you know Wetmore what's the point when you consider the abysmal state of recording today? What will we have? More accurate stuff that can be compressed?

One of the little problems with most loudspeakers that are anything like flat to even 40 KHz is that is only true exactly on axis.
 

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Well then arny, you need special Japanese speakers then!
 

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As I am not a dog with ultra-sonic hearing, I don't care a bit about the transducer producing anything above 18K. I did some A/B tests when I was in my 30's and found the "air" and "space" to be more recording correctness and care than the system. ( talking good speakers ) I do like amps that go to 40 or 50 K, as the feedback loop will stay in step at the frequencies I will actually use. I can only speak for me.


Speculation: It could be that the drivers that are clean to 40K will also have the breakup modes a lot higher, This could lead to them not falling over in the audible range causing distortion.
 

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Quote:
Originally Posted by RWetmore /forum/post/16301401


Any idea what percentage of so-called hi-rez recordings fall into this category [with unmanaged high-frequency content]?

No idea.
 

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Quote:
Originally Posted by arnyk /forum/post/16304414


I don't doubt that, espcially with close micing. Of course it seems like he tried to play you for a newbie by not citing a +/- dB spec.

Nice try, but he actually he sent me graph images that absolutely give +/- dB specs.

Quote:
Originally Posted by arnyk /forum/post/16304414


Without a +/- dB spec he could be talking about a signal that is > 100 dB down, which is never audible.

I'm well aware of this.

Quote:
Originally Posted by arnyk /forum/post/16304414


One lesser-known facts is that high frequency sounds are very rapdily attenuated over realistic distances.


According to http://www.sengpielaudio.com/calculator-air.htm


A 60 KHz tone loses 2.3 dB per meter at 25 deg C and 50% RH.

I listen to my stereo system from only about 3 meters from the speakers, so no problem there.

Quote:
Originally Posted by arnyk /forum/post/16304414


For grins estimate the distance from the first violin to your favorite seat - I'll bet its over 20 meters. That give over 100:1 loss!

I prefer the sound perspective of the conductor's podium.



Also, most recordings are engineered to give a much closer perspective than a seat 20 meters out.
 

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Quote:
Originally Posted by Chu Gai /forum/post/16303719


FWIW, you'd have to be right on top of the instrument to pick up anything of signficance and no one is going separately mic the entire ensemble and orchestra and then reconstruct a pseudo facsimile of the whole.

Huh??? You most certainly do not need to separately mic the whole orchestra to capture components above 22khz.
 

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The range of human hearing is higher than commonly reported, at least in terms of seeing a change in the brains of people hearing ultrasonics:

http://www.ocf.berkeley.edu/~ashon/a...ltrasonics.htm


"Recent work by Tsutomu Oohashi et al., published in June of 2000 in the Journal of Neurophysiology, shows that the brain may in fact be registering over-20 (or 22) kHz spectral energy. Titled "Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect", their paper discusses their finding that sounds containing High Frequency Components (HFCs) above the audible range significantly affect the brain activity of listeners."


There's a lot of information above 20 kHz.


Here's the original study:

http://jn.physiology.org/cgi/reprint/83/6/3548


This is measured, and peer-reviewed. It turns out the 20 kHz limit was incorrectly arrived at in the first place! Think what that means. For one thing, it means that every CD ever made is cutting off frequencies too early, and that listeners who complain that CDs "don't sound right" and are "fatiguing" and feel like there's a "plate of glass" in the way could be making legitimate complaints even though they can't articulate exactly what the problem is.


All those claims about how all we need is 20 kHz and a brick-wall filter, all those "scientific" dismissals based on sampling theory, all of that was based on an original sin. They. Set. The. Cutoff. Too. Low.


It also means SACD is the only source available to end users that preserves ultrasonics. And it explains why SACDs sound better than CDs.


And it also means that receivers that cut off at 20 kHz are damaging the signal.
 

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Quote:
Originally Posted by rock_bottom /forum/post/17831099


A certain neuroscientist by the name of Kal Rubinson has made some observations about the Oohashi papers here and here .

Hoo boy, I'm not going there! That entire discussion is a snakepit.


I read the original study and was impressed by the methodology and attention to detail. It would be a pain to repeat the study, but it could be done--the authors described their methodology in detail.


Mr. Rubinson says that nobody has replicated the results of the study, but what I would expect in that case are some links to the other studies that shot down the original study, or at least some abstracts. I don't see such links. That doesn't mean the other studies don't exist, but it does mean I have no rational basis for concluding the first study is wrong. I mean, we shouldn't just take Mr. Rubinson's word for it--that wouldn't be scientific!


If the study has been carefully repeated and shown to be false, that would be useful information. If the study has never been repeated, that would also be useful information, although it would be weird because the claims in the original study are so at-odds with conventional wisdom. Scientists live for the opportunity to shoot down stuff like that.


I'm actually kind of shocked that the consumer-electronics industry didn't embrace the original study (with or without corroboration) and use it as a way to sell a whole new line of Ultrasonic Capable[tm] equipment and media ("I'll have to buy the 'White Album' again"). They could have made a fortune.
 

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Quote:
Originally Posted by sk20 /forum/post/17831228


I'm actually kind of shocked that the consumer-electronics industry didn't embrace the original study (with or without corroboration) and use it as a way to sell a whole new line of Ultrasonic Capable[tm] equipment and media ("I'll have to buy the 'White Album' again"). They could have made a fortune.

I thought that was the idea of the original study (funded by an electronics company selling, among other things, speakers with super-tweeters going above 20kHz). Perhaps that was the reason nobody was interested in replicating the results.
 

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Quote:
Originally Posted by rock_bottom /forum/post/17831266


I thought that was the idea of the original study (funded by an electronics company selling, among other things, speakers with super-tweeters going above 20kHz). Perhaps that was the reason nobody was interested in replicating the results.

If that's the case, that would be sad, because that's no way to conduct science.


Just because a study is funded by Company A that desperately wishes to have Result B come out of the study doesn't mean they'll get Result B. And if they get Result B, that doesn't mean the study is wrong.


The trouble arises when Company A spikes a study that disproves (or fails to prove) Result B. In that case, the funding agent is interfering with science. I have no evidence that the company in question (I assume it's Murata) spiked any studies.


By the way, despite that discussion over on Stereophile being a snakepit, they do refer to another scientist who has found evidence that frequencies above 20 kHz matter:

http://www.physics.sc.edu/kunchur/Acoustics-papers.htm
 

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Quote:
I would expect in that case are some links to the other studies that shot down the original study, or at least some abstracts. I don't see such links.
Now you do. Essentially, this study replicated the earlier one, then showed that what the earlier researchers ascribed to ultrasonic content might actually be attributable to IM distortion below 20kHz.

Quote:
I'm actually kind of shocked that the consumer-electronics industry didn't embrace the original study (with or without corroboration) and use it as a way to sell a whole new line of Ultrasonic Capable[tm] equipment and media ("I'll have to buy the 'White Album' again"). They could have made a fortune.

A few people over the years have tried to hype that study in defense of higher sampling rates (SACD, DVD-A). That the manufacturers of those technologies did not do so suggests that the study wasn't as important to them as you might imagine. It takes more than one study to make a scientific case, especially when the researchers can't explain their results.
 

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Quote:
Originally Posted by sk20 /forum/post/17830969


The range of human hearing is higher than commonly reported, at least in terms of seeing a change in the brains of people hearing ultrasonics:

http://www.ocf.berkeley.edu/~ashon/a...ltrasonics.htm

This link appears to be broken.


The correct link appears to be:

http://www.ocf.berkeley.edu/~ashon/a...ltrasonics.htm


It appears to be a homework paper from the year 2000. It contains a number of errors of fact and logic.


It references the Ooashi paper, about which there is more information about it here:

http://en.wikipedia.org/wiki/Hypersonic_effect


Note that this is a widely-disputed paper and thus hardly reliable evidence, at least until the disputes are resolved.
 

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Quote:
Originally Posted by rock_bottom /forum/post/17831334


Yes, that Stereophile forum discussion was indeed a snake pit. There's a more thorough and civilized discussion of the Kunchur papers here .

Speaking of snake pits, a thead with similar topic and technical content to this one has gone missing in the past few days...
 

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Quote:
Originally Posted by mcnarus /forum/post/17831387

Now you do. Essentially, this study replicated the earlier one, then showed that what the earlier researchers ascribed to ultrasonic content might actually be attributable to IM distortion below 20kHz.

Hm. The study you point to says the difference is due to using a single speaker, yet:

http://www.sciencedirect.com/science...222c2a065c25aa


says the ultrasonic effect disappears with headphones but not with a single speaker. Yet headphones also have a single speaker (per ear).


Or does the study you point to claim the problem is due to intermodulation distortion between the two speakers (which wouldn't happen with headphones)?


This would seem to be something meriting further study.
 

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Quote:
Originally Posted by sk20 /forum/post/17831874


Hm. The study you point to says the difference is due to using a single speaker, yet:

http://www.sciencedirect.com/science...222c2a065c25aa


says the ultrasonic effect disappears with headphones but not with a single speaker. Yet headphones also have a single speaker (per ear).

There are massive operational differences between headphones and speakers.


Quote:
Or does the study you point to claim the problem is due to intermodulation distortion between the two speakers (which wouldn't happen with headphones)?

Here's the conclusions from the end of the paper:

Quote:
There has been a controversy about audibility of ultrasounds. In

1981, Muraoka et al.[8] used musical sounds and reported that only a

few out of 176 subjects distinguished the sounds with and without

components above 20 kHz. Several recent studies, on the other hand,

revealed that the ultrasonic components would significantly affect the

sound impression of the normal listeners. In the present study,

audibility of the components above 22 kHz was investigated under

monaural and stereophonic listening conditions.


The subjects could discriminate the stimuli with and without

ultrasounds only when all components were mixed and presented

through the same loudspeaker. When as many as 6 loudspeakers

were used in order to prevent intermodulation, no one could

discriminate the stimuli. No significant difference was found

between monaural and stereophonic conditions. It was indicated from

the results that the non-linear interaction of ultrasounds in the air or

in the auditory system was, if any, not so much as that in the average

loudspeakers as far as the level of the signal did not exceed 80 dB

SPL.


It was shown that under conditions in which experimental artifacts

had been adequately eliminated, ultrasounds would be extremely

difficult to be perceived. They may have little influence on the sound

image and its localization. Different sound impression perceived by

the subjects in the single-loudspeaker condition(Exp. 1) and in the

dual-loudspeaker condition(Exp. 2) was because of different

acoustical characteristics in the audible area due to experimental

artifacts.


In the present study, only a synthesized complex tone was used and

no data have been available for musical sounds and natural sounds

This would seem to be something meriting further study.[/quote]


I cited greisinger's further study, above:

http://www.davidgriesinger.com/intermod.ppt


That's a direct link to the study as presented. Have you studied it?

Quote:
The loudspeakers tested have intermodulation distortion lower than the threshold of detection for complex tones.

The author found audible IM elsewhere in the reproduction chain.
 

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Quote:
Originally Posted by arnyk /forum/post/17831823


Speaking of snake pits, a thead with similar topic and technical content to this one has gone missing in the past few days...

Now that you mention it, I see what you're saying.
 

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Quote:
Originally Posted by RWetmore /forum/post/16307370


Huh??? You most certainly do not need to separately mic the whole orchestra to capture components above 22khz.

First off, what does "above 22 KHz" mean. Does it mean capturing from 22 KHz to 23 KHz? No, it can't be just from 22 to 23 KHz because that would be like 1/20 of an octave which is perceptually insignificant even at 5 KHz.


How about from 22 KHz to 44 KHz with negligable losses? That's a full octave and would be signficiant other than the (disputed) ultrasonic means can't hear, thing. So for the purpose of discussion, we want reasaonbly flat response up to 44 KHz, right?


But we're back at the point where the losses at 44 KHz over concert hall distances are pretty impressive. I mean like 10s and 10s of dB being lost. You'd be very unhappy if this was going on at say 10 KHz, and isn't the idea being proposed that losses at 20KHz are something like as signfigicant as losses at 10 KHz? Maybe less, but still like 1/4 or 1/3 as important?


First off, the dimensions of a seated full orchestra may surprise you. I previously mentioned > 100:1 loss of HF information over a 20 meter or 60 foot distance.


So how large is the onstage seating area in a good sized concert hall? The answer may surprise you - 60 feet wide (proscineum opening) and 50 feet deep (proscineum to back of shell) with maybe a 10-15 foot distance from the proscinium to the lip of the stage and another 6-10 feet to the first row of seats. BTW, did you notice that the percussion instruments tend to be parked towards the back?


Oh so you don't want to sit in the front row? Well add maybe 3 feet or more for every row back.


Now check out how people minimally mic orchestras. The first row of mics are probably in the area between the proscinium and the lip of the stage. There are probably some ambience mics suspended above the seating area, maybe 1/3 or 1/2 of the way back. All the mics are at least 10-15' above the floor.


So, that 60 foot number is pretty much ballpark for minimal micing of the orchestra. And, its more like 100 feet to a good seat in the house.


Again, presuming that ultrasonic overtones are audible, if you close mic with a good wideband mic (very rare and expensive BTW) then the mic is going to get an abundance, as in 10s of dB more ultrasonics than a person would get when seated in a good seat in the house. If the recording is a DACD or high sample rate DVD-A, then the medium is going to reproduce this gross excess of ultrasonics quite well. Finally, you've seated yourself 3-6 feet from your speakers and exactly on-axis so again the losses for ultrasonics are going to be minimal.


But didn't we just figure out that our close-miced recording is going to have 10s of dBs more ultrasonics than a really good seat in the house?


Why isn't it that people with really good speakers aren't running out of their listening rooms screaming having been deafened by this probable gross excess of ultrasonics on their close-miced SACDs and DVD-As?


The reason is quite simple. The ultrasonics are truely inaudible and we can't hear whether there is 10 times too much, or 10 times too little or that they are just right.


Hey, we're still having way too much trouble getting things right *below* 20 KHz. Let's not make this Hi Fi thing even more complex than it already is!
 
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