High-Resolution Audio Listening Event at CE Week 2014 - Page 8 - AVS Forum
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post #211 of 257 Old 07-08-2014, 06:25 PM
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Originally Posted by NorthSky View Post
I have read read the full thread, twice. Thank you for the informative/instructive depictions, Arny.

...And Amir for the valiant effort.
Twice? Wow, I was feeling sorry for Brazil but now I think they had it easy, compared to you.
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post #212 of 257 Old 07-08-2014, 06:25 PM
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Originally Posted by NorthSky View Post
I have read read the full thread, twice. Thank you for the informative/instructive depictions, Arny.

...And Amir for the valiant effort.
Twice?? Wow, I was feeling sorry for Brazil but now I think they had it easy, compared to you.
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post #213 of 257 Old 07-08-2014, 07:37 PM
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Thank you; Germany had it easy. ...Very easy.

* This is an important thread, this one right here. It is the future (part of) of high-res audio.

P.S. I did read your post only twice, above.
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post #214 of 257 Old 07-08-2014, 07:42 PM
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Two words: Masochists Anonymous.
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post #215 of 257 Old 07-08-2014, 07:57 PM
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Red Book PCM (16/44) and analog 45rpm?
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post #216 of 257 Old 07-08-2014, 08:43 PM
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Originally Posted by arnyk View Post
I don't think its said as such very often. However it is well known among many lossy encoder writers that they can use a sharp roll off > 16 KHz without detracting from the transparency of their products. It must be, because that is how their products perform!
Hi Arny. Reading Chu's note about Earl talking about lack of importance for frequencies above 17 Khz, I went and found his post: http://www.diyaudio.com/forums/multi...ml#post3804975

Quote:
Originally Posted by gedlee View Post
This is why I completely discount any and all claims that above 10 kHz as perceptually important. In only a rare individual could this be detected and in almost every case real music would not be detectable. Its importance numbers simply fall to nothing. This is precisely why Perceptual coders just don't do anything above 10 kHz. Because in real testing they found that it made no difference.
Kind of interesting that you are making the same point almost word for word. Wonder if he is your source of information?

If so, I would not use Earl as an authority on audio compression. He is exceptionally strong in acoustics but audio compression is not his area of speciality. And this unfortunately a clear example of that. What he is stating is just wrong. High frequencies are most definitely dealt with in audio codecs and it presents one of the most challenging content for them to encode. Due to sharper transients, there is more chance of pre-echo. This is why as bit rates go below 128 kbps, you see the encoders truncating frequency response.

The "reference" MP3 encoder from Fraunhofer (FHG) did roll off at around 17 Khz. The guys who wrote Lame encoder relaxed that (which resulted in more distortion in lower bit rates). I remember testing the FHG encoder against the source (that was not truncated) and the reduction in the high-end was pretty clear. We were competing with MP3 using our WMA codec which did keep the full frequency response so i was pretty focused on this.

Just in case there are any doubts, here is the uncompressed frequency sweep response:



And now AAC compressed at CBR 128 kbps:



Clearly it is doing "something above 10 Khz." Response is the same as uncompressed up to 20 Khz. Audio compression would be a heck of a lot easier if we could throw out everything above 10 Khz or whatever.

The rest of his argument frankly is hard to follow too. He in one hand says his wife is an audiologist so he has seen thousands of those reports where no one could hear above 10 Khz. Only to then say that for that reason they don't test above 10 Khz. Well if they don't test above 10 Khz, how did he see reports of people's hearing above 10 Khz?

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post #217 of 257 Old 07-08-2014, 08:46 PM
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P.S. Fastest way to show that you don't know the topic of audio compression is to use terms like "encoder writers." Nobody uses such a phrase Arny. There are programmers and algorithm developers. Sometimes they are the same person working on the encoder or two different people. Neither one is called encoder writer.

Respectfully,

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post #218 of 257 Old 07-08-2014, 10:00 PM
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Inspector Clouseau?

* I want to hear from Arny, and I know that it's going to make sense.

Last edited by NorthSky; 07-08-2014 at 10:13 PM.
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post #219 of 257 Old 07-08-2014, 10:23 PM
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The mention of Earl Geddes and 17 kHz had to do with his speakers which have a fairly ratty response beyond that point. When asked about why the FR was so abysmal he said something to the effect that there was little musical information up there and what there was much lower in level compared to everything else that it would be a stretch to claim audibility.

Now, if we look at Fielder's position, not Prince Fielder who seems to have lost his mojo, he want to capture every last bit of musical information. Hi-Rez, right? So we've got to go beyond CD, go to 24 or whatever bits, use microphones that have extraordinary FR and dynamic range, and in the end, play it back on equipment with extended FR using speakers with super tweeters. Is that about right?

Geddes, and this is my interpretation, might say that all this worry about less than an octave is symptomatic of audio nervosa. He might also say the ability to get those fleeting peak levels is not a terrible thing but it just might severely limit one's choices in microphones and other do-hickeys that people recording music use.

Lastly I didn't particularly like the 'subtle' suggestion that Arny was plagiarizing Earl's comments.

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post #220 of 257 Old 07-08-2014, 10:29 PM
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Quote:
Originally Posted by Chu Gai View Post
...
Lastly I didn't particularly like the 'subtle' suggestion that Arny was plagiarizing Earl's comments.
I must confess; I was also disappointed. ...And other points too.
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post #221 of 257 Old 07-09-2014, 02:37 AM
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Quote:
Originally Posted by NorthSky View Post
Inspector Clouseau?

* I want to hear from Arny, and I know that it's going to make sense.
Thanks for the encouragement.

Here is the link for my idea of killer 24/96 .wav files files for using ABX to hear potential audible differences due to differences in bandpass and resolution:

https://www.dropbox.com/sh/l86f7oc7c...ww14Mrta1zs3Ca

Be careful with these files - the full bandpass version has so much ultrasonic energy that it can possibly take out your tweeters and you won't even think that it is playing very loud. They are also highly diagnostic for high frequency IM.

Full bandpass:



Band and resolution limited to 44/16:



Band and resolution limited to 32/16:



Listen away guys! If you can't hear a difference between these files, hang it up...

The source is my keychain ca. Y2K being jangled about a foot away from a DPA 4006 measurement mic, as precisely on axis as I could get it in a low reverberent room. This particular test has been well known among studio engineers for about half a century, and it has the advantage that for testing microphones and speakers, the only special test equipment has the right price!
Attached Thumbnails
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post #222 of 257 Old 07-09-2014, 02:45 AM
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Quote:
Originally Posted by Chu Gai View Post
The mention of Earl Geddes and 17 kHz had to do with his speakers which have a fairly ratty response beyond that point.
That is characteristic of compression drivers. Coincidentally Earl mentioned that at our 4th of July get together at Dave's house.

The science is that compression drivers are caught between a rock and a hard place. You want the diaphragm snuggled up right against the phasing plug for high frequency response, and you want it as far away as possible for low frequency dynamic range. This is general knowlege for decades among the people who use these things.

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post #223 of 257 Old 07-09-2014, 03:07 AM
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Quote:
Originally Posted by amirm View Post
Hi Arny. Reading Chu's note about Earl talking about lack of importance for frequencies above 17 Khz, I went and found his post: http://www.diyaudio.com/forums/multi...ml#post3804975

Quote:
Originally Posted by Earl Ge3ddes
This is why I completely discount any and all claims that above 10 kHz as perceptually important. In only a rare individual could this be detected and in almost every case real music would not be detectable. Its importance numbers simply fall to nothing. This is precisely why Perceptual coders just don't do anything above 10 kHz. Because in real testing they found that it made no difference.
Kind of interesting that you are making the same point almost word for word. Wonder if he is your source of information?
Here's a news flash Amir. Earl and I live in the same universe and through the magic of science we often end up seeing the same things.

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If so, I would not use Earl as an authority on audio compression.
I didn't. The interjection of Earl into this discussion at this point is entirely your doing.

The above post is a classic example of crass propaganda. First you accuse me of plagiarizing Earl and then you poison the Earl well. I think I can find a Goebbels speech that does the same thing! ;-)

Are perceptual coder writers still sacrificing big wads of response below 22 KHz?

I just looked at a bunch of files I ripped just lately and coded with the latest version of Lame @ 256 kbps. All cut off quite nicely at 19 KHz, some 3 KHz short of 22 KHz. Sure, the practice is not universal, but it is still being done by people who should know better, if not doing it is knowing better.

I say, let people believe the evidence of their ears.

There's a new batch of 24/96 files with brick walls @ 48, 22 and 16 Khz posted at https://www.dropbox.com/sh/l86f7oc7c...ww14Mrta1zs3Ca.

ABX away, but at your own risk! ;-)

Last edited by arnyk; 07-09-2014 at 03:32 AM.
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post #224 of 257 Old 07-09-2014, 03:32 AM
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Arny, just looking at the Frequency Analysis pictures above.

What do you think causes the visual differences in the lower frequencies among the three?

I'll be back later...


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post #225 of 257 Old 07-09-2014, 03:36 AM
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Originally Posted by RayDunzl View Post
Arny, just looking at the Frequency Analysis pictures above.

What do you think causes the visual differences in the lower frequencies among the three?
Some of the files were not analyzed over the same section of the basic audio file. I was trying to make a point about the high frequency content, and kinda skipped over getting the analysis regions lined up perfectly. Good eye!

Also notice that the amplitudes of the files are vastly different. I think that the Replaygain numbers will be all over the map as well.

Hold your nose and ABX them! ;-)

Last edited by arnyk; 07-09-2014 at 04:40 AM.
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post #226 of 257 Old 07-09-2014, 07:42 AM
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Quote:
Originally Posted by arnyk View Post
Here is the link for my idea of killer 24/96 .wav files files for using ABX to hear potential audible differences due to differences in bandpass and resolution:

https://www.dropbox.com/sh/l86f7oc7c...ww14Mrta1zs3Ca
Good morning Arny. I was going to say "thank you" for posting these files but after having to listen to jingling keys so many times while our two dogs barked and barked away, not sure I am that thankful .

Here are my results:

32 Khz versus 96 Khz
=================================
foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/09 06:10:07

File A: C:\Users\Amir\Music\Arnys Filter Test\keys jangling band resolution limited 3216 2496.wav
File B: C:\Users\Amir\Music\Arnys Filter Test\keys jangling full band 2496.wav

06:10:07 : Test started.
06:10:38 : 01/01 50.0%
06:10:50 : 02/02 25.0%
06:11:07 : 03/03 12.5%
06:11:23 : 04/04 6.3%
06:11:36 : 05/05 3.1%
06:12:00 : 06/06 1.6%
06:12:14 : 07/07 0.8%
06:12:26 : 08/08 0.4%
06:12:38 : 09/09 0.2%
06:12:49 : 10/10 0.1%
06:13:00 : 11/11 0.0%
06:13:23 : 12/12 0.0%
06:13:42 : 13/13 0.0%
06:13:48 : Test finished.

----------
Total: 13/13 (0.0%)


44.1 versus 96 Khz
---------------------------------

foo_abx 1.3.4 report
foobar2000 v1.3.2
2014/07/09 06:32:02

File A: C:\Users\Amir\Music\Arnys Filter Test\keys jangling band resolution limited 4416 2496.wav
File B: C:\Users\Amir\Music\Arnys Filter Test\keys jangling full band 2496.wav

06:32:02 : Test started.
06:33:07 : 01/01 50.0%
06:33:17 : 02/02 25.0%
06:33:24 : 03/03 12.5%
06:33:36 : 04/04 6.3%
06:33:47 : 05/05 3.1%
06:33:58 : 06/06 1.6%
06:34:12 : 07/07 0.8%
06:34:15 : Test finished.

----------
Total: 7/7 (0.8%)

===============================

I don't know why Foobar stopped all of a sudden at 7 trials on 44.1 vs 96. While I could clearly hear the difference between the files, I would want to run more trials later as I did not expect to be able to tell them apart this easily.

Anyway, how did you do Arny?

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post #227 of 257 Old 07-09-2014, 01:56 PM
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Quote:
Originally Posted by Chu Gai View Post
Now, if we look at Fielder's position, not Prince Fielder who seems to have lost his mojo, he want to capture every last bit of musical information. Hi-Rez, right? So we've got to go beyond CD, go to 24 or whatever bits, use microphones that have extraordinary FR and dynamic range, and in the end, play it back on equipment with extended FR using speakers with super tweeters. Is that about right?

A thing about truly high dynamic range recordings -- typically classical -- is that a lot of listeners in a lot of home audio listening environments will complain that when they 'turn it up' enough to hear the quiet parts, the loud parts become overbearing.
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post #228 of 257 Old 07-09-2014, 02:39 PM
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Maybe we can compress things a bit.

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
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post #229 of 257 Old 07-09-2014, 02:43 PM
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Maybe we can compress things a bit.

Exactly. It's the circle of life. We forget the things we knew, and invent them again.
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post #230 of 257 Old 07-09-2014, 07:58 PM
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Originally Posted by krabapple View Post
A thing about truly high dynamic range recordings -- typically classical -- is that a lot of listeners in a lot of home audio listening environments will complain that when they 'turn it up' enough to hear the quiet parts, the loud parts become overbearing.
Not surprised, even rooms that people think are quiet have a higher noise floor then they realize. A living room is not like a concert hall.

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post #231 of 257 Old 07-09-2014, 08:34 PM
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Originally Posted by tenthplanet View Post
Not surprised, even rooms that people think are quiet have a higher noise floor then they realize. A living room is not like a concert hall.
Turns out our home listening spaces are far better than we think. See this article I wrote on that: http://www.madronadigital.com/Librar...amicRange.html

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post #232 of 257 Old 07-09-2014, 09:06 PM
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Not surprised, even rooms that people think are quiet have a higher noise floor then they realize. A living room is not like a concert hall.
A concert hall can very well be worse for listeners. Recordings are made when they're empty.
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post #233 of 257 Old 07-09-2014, 09:39 PM
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Amirm doesn't have an apartment in the projects.

(Neither do I)

Generally, the biggest noise I get here is 6am when the course maintenance people fire up the machines to scalp the 3rd green and 4th tee.

I'll be back later...


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post #234 of 257 Old 07-10-2014, 01:31 AM
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A concert hall can very well be worse for listeners. Recordings are made when they're empty.
But they have better sound isolation from the outside world then the average home.

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post #235 of 257 Old 07-10-2014, 04:52 AM
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Quote:
Originally Posted by amirm View Post
Turns out our home listening spaces are far better than we think. See this article I wrote on that: http://www.madronadigital.com/Librar...amicRange.html
IMO you exaggerate the importance of HDMI jitter while simultaneously understating the importance of a low noise floor in a listening room. I find that a bit baffling since the addition of acoustical room treatments and sound isolation are among the best sound-quality upgrades you can make, for any system.

I disagree with the final quote in your article: "two ears and a brain are much more analytical than a microphone and a meter!" Whose ears are referred to in that quote? Anyone's ears? Or a trained pair of exceptional golden ears, as verified through ABX testing?

If that's really true that ears beat a mic and a meter (which for the sake of argument is a computer running measurement software), can you explain why it's so difficult for two ears and a brain to accurately measure sound levels, distortion, frequency range, and etc.? It sounds like the same argument made by the guys who think they can calibrate a TV by sight, instead of using a meter.

Personally, I'd go with "two ears and a brain are a lot more holistic than a mic and a meter"

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post #236 of 257 Old 07-10-2014, 05:14 AM
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Originally Posted by imagic View Post
IMO you exaggerate the importance of HDMI jitter while simultaneously understating the importance of a low noise floor in a listening room. I find that a bit baffling since acoustical room treatments are among the best sound-quality upgrades you can make.

I disagree with the final quote in your article: "two ears and a brain are much more analytical than a microphone and a meter!" Whose ears are referred to in that quote? Anyone's ears? Or a trained pair of exceptional golden ears, as verified through ABX testing?

If that's really true that ears beat a mic and a meter (which for the sake of argument is a computer running measurement software), can you explain why it's so difficult for two ears and a brain to accurately measure sound levels, distortion, frequency range, and etc.? It sounds like the same argument made by the guys who think they can calibrate a TV by sight, instead of using a meter.
The statement: "two ears and a brain are much more analytical than a microphone and a meter!" is yet another straw man argument.

As you correctly point out, a microphone and a meter is not the full extent of even fairly inexpensive audio measurement facilities. As usual, the writer pretends that the facilities he apparently doesn't like are brain dead in order to make a false point.
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post #237 of 257 Old 07-10-2014, 05:20 AM
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But they have better sound isolation from the outside world then the average home.
People seem to generate ambient noise in any public setting that far exceeds my home environment.

The vast majority of recording have the life compressed out of them. IMO, Reducing compression should be a goal of HD audio. It would be nice if CD's had used even half of the capabilities of 44.1/16.

I want it to sound like the musicians are in the room and spend what I consider considerable effort and funds to that end.

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post #238 of 257 Old 07-10-2014, 05:29 AM
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Originally Posted by RichB View Post
People seem to generate ambient noise in any public setting that far exceeds my home environment.
I have over a decade of experience with measurements of SPLs in performance spaces when they are empty, have an audience present, have an audience + musicians present, and when there is actually music being played for an audience. I even have some recordings of music being played for a vanishing audience. The bottom line is that musicians create a lot of noise when they play, or even sit at rest in the midst of playing. Clothing rumples, breathing intensifies, etc. It sounds very much like random noise.

There's a scientific law of signals analysis that reiterates the common sense idea that the statistics of a large number of independent noise sources tends to converge to randomness, and my observations back that up.
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post #239 of 257 Old 07-10-2014, 06:18 AM
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Originally Posted by krabapple View Post
A concert hall can very well be worse for listeners. Recordings are made when they're empty.
Concert halls and recording studios are not empty when recordings are made. The musicians are there. The musicians can be pretty noisy - they move their limbs, their clothing rustles and they breathe. There may be 100 or more, and the mics are all aimed at them and/or are in close proximity to them.
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post #240 of 257 Old 07-10-2014, 06:34 AM
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Originally Posted by imagic View Post
IMO you exaggerate the importance of HDMI jitter while simultaneously understating the importance of a low noise floor in a listening room. I find that a bit baffling since the addition of acoustical room treatments and sound isolation are among the best sound-quality upgrades you can make, for any system.

I disagree with the final quote in your article: "two ears and a brain are much more analytical than a microphone and a meter!" Whose ears are referred to in that quote? Anyone's ears? Or a trained pair of exceptional golden ears, as verified through ABX testing?

If that's really true that ears beat a mic and a meter (which for the sake of argument is a computer running measurement software), can you explain why it's so difficult for two ears and a brain to accurately measure sound levels, distortion, frequency range, and etc.? It sounds like the same argument made by the guys who think they can calibrate a TV by sight, instead of using a meter.

Personally, I'd go with "two ears and a brain are a lot more holistic than a mic and a meter"
Thank you for your comments. Alas, it is an emotional response based on what I call "forum science." When presented with real science that disputes the "common forum wisdom" the reaction is always the same: denying the science! And blaming the messenger.

In this case you were reading a published paper. Thousands of people have read it there and not one person had written in to say, "this is all wrong." On the contrary, when I go to trade shows people always compliment me on a few of my papers and this is one of them.

I wish I could take credit for the knowledge within that article but alas, I can't. I am standing on tall shoulders of luminaries in audio science. They are listed in the references:

References
“Noise: Methods for Estimating Detectability and Threshold,” Stuart, J. Robert, JAES Volume 42 Issue 3 pp. 124-140; March 1994
“Dynamic-Range Issues in the Modern Digital Audio Environment,” Fielder, Louis D., JAES Volume 43 Issue 5 pp. 322-339; May 1995

Note that both papers are Journal of AES which means they were "peer reviewed." If peer reviewed means folks can write exaggeration then we might as well never reference anything at AES.

If you have disagreement with the research, by all means, make your case with data and references as I have done. Saying, "nah, nah, nah" is not an answer. I could claim earth is flat the same way. That doesn't make it right.

As to the specific references to two ears and a brain, think of this simple thought experiment. Think back to hearing your loved ones in different rooms in your house. Did they sound radically different? I bet not. They had the same familiar voice no matter if they were in your living room or bathroom. If you measure with a microphone, her voice would measure very differently. The room reflections are wildly different causing different frequency response and amplitudes which the meter "faithfully" records. Problem is, it is all a lie. As I just mentioned, what you perceive is that your loved one's voice is the same. Not what the meter is telling you.

The confusion comes from the fact that there are two parts to human hearing:

1. Detecting the sound. This is determined by the anatomy of your ear, face, etc.

2. Perceiving the sound. This is the cognitive, i.e. thinking part of your brain which kicks in to make sense out of incredible amount of data being transmitted by the ear. You would go crazy if you actually "heard" all that comes in. The brain performs analysis and decided what is useful, what is not. In the case of your loved one, the brain has learned that the room reflections are "constant" and lack useful information so it tunes them out. And focuses on what your loved one is saying which is the important thing you are interested in hearing.

If you want to read more, I have written an article on that too . You will likely blow a second fuse after reading it in how it tears apart your conceptions of audio and room acoustics: http://www.madronadigital.com/Librar...flections.html

You ask about the meter being more accurate. What is accuracy? That some electrical signal resulted in some numerical value? Why would I care about that? What I care is measurements that tell me what I am hearing. A 3 db increase in power means you have twice as much power. The meter will confirm this. Except that to actually perceive twice the loudness you need 10 db. So the db numbers are clearly a "lie."

As for video vs audio, let's not at all go there. Video is designed "right." It has a reference that we can compare all of our playback systems. We indeed point a meter and get what was recorded to match what is being played. The two systems are then the same and we are seeing (in theory anyway) what the talent did when approving said content in front of the colorist.

Audio in comparison is a busted mess. You hear guitar being played in your system. There is no way that is sounding the same as the guitar being played live. Even if it did, you cannot prove that. This is why we have so many debates in audio that don't get resolved. Ultimately you can't prove which system is truer to the source. We could flip a coin and fix this by recording metadata that would characterize the recording and match it in playback. But it is not being done.

It is because of the standards in video that we get to use the colorimeter because that is what was used to calibrate the recording system. By using the same tool we can (in theory again) match our playback system to recording. An SPL meter is a joke when applied in audio. Other than its use for movie levels where we have that standard (sadly only level and nothing else), and measuring frequencies below transition to plot our frequency response, it has little to no other use. You better not use it above a few hundred hertz or else, you would be violating psychoacoustics.

Finally as to “two ears and a brain” being better than a meter, I wish I was smart enough to have invented that but I am not. Here is the reference in my article:

By the way, much of this was probably intuitively obvious as you noticed how quiet your room was despite the high SPL numbers shown on the meter. As Dr. Toole, one of the top experts in acoustics and speaker design is fond of saying, “two ears and a brain are much more analytical than a microphone and a meter!” Indeed, your ears told the truth better than the measurement device.

Dr. Toole is an incredible authority here since he is the only acoustics expert who started as a psychoacoustics major and researcher. His ability to combine those two fields together with a ton of data ins unrivaled in the industry/research community. You can learn more about audio than a lifetime spent on forums by reading his superb book on the topic: http://www.amazon.com/Sound-Reproduc...ds=floyd+toole. $43 will make you smarter than just about everyone here who has not read the book .

Here is a choice quote on this very topic:

What is missing from this perspective is that two ears and a brain
are far more analytical than an omnidirectional microphone and an analyzer.

The measurement system simply adds up all sounds, from all directions, at all
times, and renders a single curve. A loudspeaker turned to face the wall, after
equalization, should sound like that same loudspeaker facing the listeners. It
doesn’t. There is insufficient data to describe the source and thereby how it
interacts with the room boundaries. Humans have a remarkable ability to separate
a source from the room it is in and offer up detailed descriptions of how
it sounds, even when the room is changed (see Chapter 11). We need measurements
that describe the nature of the source and that provide insight into what
happens in a room.


If you want to practice pseudo science, by all means stomp your feet and say I am wrong based on what you have read on a forum and what made sense to your gut. But if you want to practice real science, expand your knowledge with reading above book and countless other references I provide in these posts and use them to back your views.

Did you run Arny’s test by the way? Please post your results.

Amir
Retired Technology Insider
Founder, Madrona Digital
"Insist on Quality Engineering"
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