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Topic: Audibility of "typical" Digital Filters in a Hi-Fi Playback  (Read 367804 times) previous topic - next topic
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Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #900
Does anyone know the crossover frequency for the tweeter in the speaker that was used in this paper?
"I hear it when I see it."

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #901
As to his theory of IM distortion, it is just that: some theory.
That's a surprising statement in this context!
IM distortion from ultrasonic signals, measurable in most hi-fi speakers on the planet, and laughably easy to hear with various signals, is just some theory? Yet the audibility of ultrasonic ringing, suggested but not proven as the reason a filtered signal could be picked out 10% better than random choice in one study, is the important thing?
I would suggest that you can either pick evidence to suit your claims while ignoring evidence that does not, or complain that people aren't being objective. But you can't get away with doing both. In the same thread.
It's really disappointing, because it looked like you wanted to explore all avenues and possibilities when you started posting, but it seems that you weigh evidence by how much it supports your pre-decided conclusions, rather than by any objective criteria.

Cheers,
David.


Wow David, can't you see how clear the objective answer to your IM audibility/false positive concerns, is.....the BS paper won an award!!! From the AES!!
What does the possibility of false positives matter, when the BS paper won an AES award from 2 reviewers who didn't review the entire manuscript?

cheers,

AJ
Loudspeaker manufacturer

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #902
It really can't be said often enough to ask about more data especialy about the metal tweeter.
I am not part of amirs professionel parallel universe but i often had surprises with building speakers with metal domes.
There was some self-sound mostly unpleasant that was not to measure with simple frequency responses.
It wouldn't come as a surprise to me if the tested filters only triggered a material resonance differently.
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #903
Does anyone know the crossover frequency for the tweeter in the speaker that was used in this paper?


Probably not too much different from other speakers in their product line:

http://www.stereophile.com/content/meridia...-specifications

"Crossover frequencies: 200Hz, 2.6kHz

Looking at the lab tests, those numbers might be approximations:

http://www.stereophile.com/content/meridia...er-measurements



Suggests an actual crossover to the midrange @185 Hz

and



suggests a crossover to the tweeter @ 3 Khz  (a surprisingly amateurish off-axis dip is the tell.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #904
It really can't be said often enough to ask about more data especialy about the metal tweeter.
I am not part of amirs professionel parallel universe but i often had surprises with building speakers with metal domes.
There was some self-sound mostly unpleasant that was not to measure with simple frequency responses.
It wouldn't come as a surprise to me if the tested filters only triggered a material resonance differently.



The worst thing I see in many metal domed speaker drivers is that massive high Q resonance in the 20-25 KHz range.  Engineering 101 -  high Q resonances ruin transient response. Even if a listener could hear pre-ringing at 22 KHz due to a linear phase reconstruction filter, how would one do so in the face of massive oscillation of the tweeter dome?

Dome tweeters can be pretty counter-intuitive. There are numerous examples of soft dome tweeters with on-axis response that is only a few dB down @ 40 KHz.

https://www.madisoundspeakerstore.com/ring-...diator-tweeter/


Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #906
As to his theory of IM distortion, it is just that: some theory.
That's a surprising statement in this context!

IM distortion from ultrasonic signals, measurable in most hi-fi speakers on the planet, and laughably easy to hear with various signals, is just some theory?

Yes because if you read Monty's blog, it has no measurements or test cases whatsoever.  If this is a real problem, real examples need to be given.

The theory also ignores the amplitude of ultrasonics in music.  We can see that in the sample music in Stuart's paper:

Amir
Retired Technology Insider
Founder, AudioScienceReview.com

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #907
https://www.madisoundspeakerstore.com/ring-...diator-tweeter/

One of the best tweeters ever build imho.



Interestingly enough there are a number of versions of it some very conventional-looking:

https://www.madisoundspeakerstore.com/soft-...e-dome-tweeter/



which have similar measured frequency response. The above unit is only 3 dB down from its 3 KHz level on axis @ 30 KHz.

I have a pair of Primus PC351s with this tweeter, forced on me by the failure of the OEM drivers.  The OEM drivers had exotic hard diaphragms and tests show the not-unexpected HF resonance. These are soft domes and are pretty flat.  I make no special claims.

There are some funny stories about the origin of soft domes. For one, it is claimed that the first soft domes were made as show exhibit pieces to avoid the fact that nobody can avoid poking at domes and denting them. They guy who built them figured that no way could they have any treble, but just for fun he measured them. They were about as smooth and extended as anything. 



Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #909
Quote
CONCLUSIONS

3. Our findings are consistent with the idea that
filters with long impulse responses blur fine tem-
poral details of signals. [The idea is diminished in persuasiveness given that the filtering was of ultrasonic frequencies using linear phase.]



Agreed.

This finding may be further diminished by the fact that the test involved filters with unrealistically narrow transition bands that lead to unrealistically large  amounts of ringing, and that the metal dome tweeters used may have masked the behavior of the filter with their own ringing.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #910
the fact that the test involved filters with unrealistically narrow transition bands that lead to unrealistically large  amounts of ringing,


A fact that you doubtless verified, e.g. by visiting src.infinitewave.ca, assessing the transition band width of those SRCs that are 1) commonly used in music production and 2) not obviously broken by ^*%&$^ design.


Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #911
the fact that the test involved filters with unrealistically narrow transition bands that lead to unrealistically large  amounts of ringing,


A fact that you doubtless verified, e.g. by visiting src.infinitewave.ca, assessing the transition band width of those SRCs that are 1) commonly used in music production and 2) not obviously broken by ^*%&$^ design.



I did it the old fashioned way - read the Meridian AES conference paper (which said that the transition bands they used were ca. 500 Hz) and studied a number of spec sheets for DAC chips that are likely to be used in modern medium and high quality gear. 

I also measured the transition bands in the SRC I used the most - CoolEdit Pro 2.1. 

CoolEdit has a quality adjustment for its SRC. The lowest quality filtering @ 44.1 KHz gives  a transition band of about 1.8 KHz - a lot like a real world DAC, while the highest quality setting gave a transition band of about 5 Hz.

Quote from the Meridian paper:

"The frequencies of the transition bands were 23500-
24000 Hz and 21591-22050 Hz, corresponding to the
standard sample rates of 48 kHz and 44.1 kHz respectively.4
"

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #912
A fact that you doubtless verified, e.g. by visiting src.infinitewave.ca, assessing the transition band width of those SRCs that are 1) commonly used in music production and 2) not obviously broken by ^*%&$^ design.


Hopefully the masters use ultra steep linear phase settings, because then your DAC's or player's (resampling) filter will completely dominate the output.

This also explains why they had to use 192 kHz all the way... otherwise their 44.1 kHz apodizing filter would have eliminated 21+ kHz pre-ringing during playback.
"I hear it when I see it."

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #913
Yes because if you read Monty's blog, it has no measurements or test cases whatsoever.  If this is a real problem, real examples need to be given.

Some recent tests using Monty's IM files: https://www.gearslutz.com/board/10576574-post9.html

And we should care about near clipping distortion at 30/33Khz why?




Amir
Retired Technology Insider
Founder, AudioScienceReview.com

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #914
The point is that a great many mastering tools have a transition band narrower than the paper's 500Hz. Often much narrower.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #915
The point is that a great many mastering tools have a transition band narrower than the paper's 500Hz. Often much narrower.

So?

The paper is about simulating real-world anti-imaging filters, not resampling filters.
"I hear it when I see it."

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #916
The point is that a great many mastering tools have a transition band narrower than the paper's 500Hz. Often much narrower.


Examples?

Not that I doubt it, as some of the tools I have are exactly thtat way.

The bad news for the Meridian boys is if the mastering people put ringing into the masters, what takes it out?  As I read their materials, their Apodizing filters span of correction is the ringing in the filters in their own equipment.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #917
Quite frankly, unless you're an outright con man/shyster type selling $50k+ audio jewelry and trying to further profit from the Hi-Re$ $cam, the BS paper has more holes than swiss cheese.
Completely contrived dither, zero data on system transparency, a high likelihood of system generated artifacts (especially metal dome tweeter driven to 108db), zero switching transparency data, time alignment, etc, etc.
As I noted earlier, it will be interesting how High End Shysters Inc. sells this BS test to the $cam addicts, when they reject any honesty controls/level matched blind tests as valid. Instead opting for purely subjectivist delusion filled sighted "comparisons" of amps, DACs, etc. and some rather hilarious stuff like +/-10% level fiddling "tests" to determine audibility of said delusions.

cheers,

AJ
Loudspeaker manufacturer

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #918
As to his theory of IM distortion, it is just that: some theory.
That's a surprising statement in this context!

IM distortion from ultrasonic signals, measurable in most hi-fi speakers on the planet, and laughably easy to hear with various signals, is just some theory?

Yes because if you read Monty's blog, it has no measurements or test cases whatsoever.  If this is a real problem, real examples need to be given.

The theory also ignores the amplitude of ultrasonics in music.  We can see that in the sample music in Stuart's paper:



The spectrum above 22/24 Khz is what, 90 db lower than peak in the in-band?  IM distortion would be a percentage of this so it will be at even lower levels.

Here is the IM distortion test tracks Arny had us run which we passed with no audible IM detected:



His ultrasonic test tone pairs on the right are nearly clipping level.  Yet they still did not garner detection in the sampling of people who ran it.



I'm beginning to think that there were two mechansims that dominated these experiences:

(1) Audio interfaces and PC's that did internal downsampling and thus killed the test tones before they tested anything.  I've found a lot of these in my explorations.

(2) People whose hearing or perceptions that were such that they didn't perceive troublesome artifacts that many experienced listeners would find to be highly audible.

The  claim that artifacts due to the HF test tones were totally undetected is questionable. I surely heard artifacts due to the test tones in my tests, and I seem to recall that there were some people who switched their test setups after I put out the first set of HF IM tests.  I have at least one private report that sounds all the world to me like a monitoring system that failed the test, along with strong assertions that what they heard was OK.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #919
What takes the ringing out? Well, their apodizing filter would if the data were fed to their DSP at 44.1 kHz.
"I hear it when I see it."

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #920
The bad news for the Meridian boys is if the mastering people put ringing into the masters, what takes it out?  As I read their materials, their Apodizing filters span of correction is the ringing in the filters in their own equipment.
No, if the ringing is at the Nyquist frequency of the delivered digital audio, the Apodizing filter will remove it. As would any low pass filter that cuts below the original Nyquist frequency when upsampling. However, the point of the Apodizing filter is that it doesn't pre-ring itself. Most upsampling filters would.

I don't claim it's audible. I'm just explaining how it works.

Cheers,
David.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #921
If we are objectivists, we better be objectivists all the time.
Good. Then can we agree on these things? Or not?

1. The BS paper reports a listening test where the filtering was detected 10% better than chance (which, in the number of trials performed, is statistically significant)
2. The different scenarios tested all gave broadly similar results overall.
3. Some differences between scenarios became larger when the data was post-sorted and re-analysed, but the rigorous way of investigating this is to re-test these apparently better conditions, not post-process the data looking for the better conditions after the fact.
4. There was no re-test, so at this stage we shouldn't claim differences between filter types, dither, etc.
5. The theories as to why/how the filtered samples were differentiated from the original samples are just that: theories. It would be possible to design listening tests to probe these theories, but this has not been done. At this stage, we shouldn't claim the filtering was audible because of X, Y or Z.
6. No one has done a listening test to probe the audibility of ultrasonic ringing itself. (AFAIK - do you know different?)
7. Audible IMD from ultrasonic signals is readily demonstrable under certain circumstances.
8. The worst audible IMD from ultrasonic signals is far more easily audible than the worst effects of ultrasonic ringing from the "worst" "CD" sinc filter.
9. Measurable IMD from ultrasonic signals reduces with ultrasonic signal level, often almost proportional to some positive integer power of the signal level, rather than linearly. (i.e. it falls away surprisingly quickly).

My objective conclusion from all the evidence is that neither mechanism should be readily audible, but in a test where people were just about able to hear some kind of difference, that difference could be down to one, the other, both, or neither - pending further investigation.


As someone else has already mentioned, Sony put (switchable!) filters on the output of their SACD players. This is an admission that it will sometimes be better to remove ultrasonic signal components, long before Monty mentioned it.


The fact ultrasonic signal components can have unintended consequences in the audible range due to equipment non-linearities is basic maths and well understood. People have known this for decades. Monty didn't make it up!

The possibility that pre-ringing in ultrasonic filters could be audible is possibly related. It's also something some people have been saying for a decade or so. There's no maths or (currently) psychoacoustics to back it up. This is the first test to properly look at it, and we can't reach any conclusions yet.


Please note which one of these is established fact, and which one is as-yet unproven theory.

Cheers,
David.

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #922
If we are objectivists, we better be objectivists all the time.
Good. Then can we agree on these things? Or not?

1. The BS paper reports a listening test where the filtering was detected 10% better than chance (which, in the number of trials performed, is statistically significant)
2. The different scenarios tested all gave broadly similar results overall.

Agree.
Quote
3. Some differences between scenarios became larger when the data was post-sorted and re-analysed, but the rigorous way of investigating this is to re-test these apparently better conditions, not post-process the data looking for the better conditions after the fact.

It is routine to perform such post-process analysis.  Excluding Simpson's paradox is a good thing, not bad.

Quote
4. There was no re-test, so at this stage we shouldn't claim differences between filter types, dither, etc.

But we can say that the claim that "no double blind test has shown differences of this type" or that "the distortions are below JND" have been falsified.

Quote
5. The theories as to why/how the filtered samples were differentiated from the original samples are just that: theories. It would be possible to design listening tests to probe these theories, but this has not been done. At this stage, we shouldn't claim the filtering was audible because of X, Y or Z.

Correct.
Quote
6. No one has done a listening test to probe the audibility of ultrasonic ringing itself. (AFAIK - do you know different?)

This may be indicative of that.

Quote
7. Audible IMD from ultrasonic signals is readily demonstrable under certain circumstances.

In double blind tests with music as opposed to near clipping tones?

Quote
8. The worst audible IMD from ultrasonic signals is far more easily audible than the worst effects of ultrasonic ringing from the "worst" "CD" sinc filter.

There is no data on record to represent this.  The testing in Stuart's paper used music.  The only test provided for IM distortion has near clipping ultrasonic tones which has no music profile that matches it.

Quote
9. Measurable IMD from ultrasonic signals reduces with ultrasonic signal level, often almost proportional to some positive integer power of the signal level, rather than linearly. (i.e. it falls away surprisingly quickly).

Correct.  And given the fact that the level of ultrasonics also drop sharply on their own, makes the IM distortion an unlikely cause.

Quote
My objective conclusion from all the evidence is that neither mechanism should be readily audible, but in a test where people were just about able to hear some kind of difference, that difference could be down to one, the other, both, or neither - pending further investigation.

Agree.

Amir
Retired Technology Insider
Founder, AudioScienceReview.com

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #923
As someone else has already mentioned, Sony put (switchable!) filters on the output of their SACD players. This is an admission that it will sometimes be better to remove ultrasonic signal components, long before Monty mentioned it.

Sorry no.  Removing quantization noise shoved in ultrasonic range is a good thing.  It can cause amplifier oscillation and potential damage to the tweeter. 

That is not the same as chopping off spectrum of music at the low levels that exists in ultrasonic range.

.
Amir
Retired Technology Insider
Founder, AudioScienceReview.com

 

Audibility of "typical" Digital Filters in a Hi-Fi Playback

Reply #924
Actually Monty (and Jean-Marc Valin of xiph.org) rebutted you (and patiently rebutted all manner of tendentious nonsense from your acolytes) over and over on your forum; you simply refused to accept it (an admitted at one point that you tend not to acknowledge error because 'it's two males') and performed your usual dance steps.

Monty nailed the fallacy in your overall thesis re: the 'need' for hi rez,  *back in 2012*:

http://www.whatsbestforum.com/showthread.p...ll=1#post108311


Quote
What you are advocating is being unable to sell better masters to an audiophile without the added expense of senseless recording overkill, because said audiophiles have been 'educated' that they need a gold plated Hummer with artillery mount to drive to the corner store.

Is this a benefit to the industry? to anybody?



I found your dance steps about wanting to hear the *ultrasonics-induced intermodulation distortion that was heard and approved in the studio* (!)  particularly amusing.