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What Do We Mean By Audible - A Slide Show

post #1 of 24
6/27/07 at 2:21pm
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Click here.
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post #2 of 24
6/27/07 at 4:58pm
WHAT????

SPEAK UP!!!



No, but that was an interesting slideshow, I hope people go through it.

One serious criticism though, is that the trial being discussed has to do with volume change, and then there is the bullet point which states:

"In the case of 20-bit vs 24 bit, the actual change in voltage is less than 1/10,000th of 1%"

...which insinuates that such a difference is not audible, but that does not relate to the question being tested which is differentiating volume.
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post #3 of 24
6/27/07 at 5:18pm
Interesting.

I remember that 0.3dB is the figure used for definitive discriminatory tests.... so I wonder why the autor used 0.4 dB instead.
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post #4 of 24
6/27/07 at 6:30pm
Quote:
Originally Posted by ChrisWiggles View Post

One serious criticism though, is that the trial being discussed has to do with volume change, and then there is the bullet point which states:

"In the case of 20-bit vs 24 bit, the actual change in voltage is less than 1/10,000th of 1%"

...which insinuates that such a difference is not audible, but that does not relate to the question being tested which is differentiating volume.

Yeah. That sorta stuck out like a sore thumb to me, too.
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post #5 of 24
6/27/07 at 8:23pm
Since the statistical data in his small experiment get down to an almost random point, I don't see that it would be affected much by .3db versus .4. You're already at an "almost" random result and need more people and trials. Pls comment?

I was confused by this comment: "In the case of 20-bit vs 24 bit, the actual change in voltage is less than 1/10,000th of 1%"

...which insinuates that such a difference is not audible, but that does not relate to the question being tested which is differentiating volume."

I would have thought that if you are an order of magnitude or two beyond the .4db that expecting that diff to be audible is awfully unlikely. So, it's more than an insinuation. What am I missing?

Rgrds-Ross
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post #6 of 24
6/27/07 at 9:01pm
Wouldn't it be more interesting to say, oh... set up some tests and do some listening experiments instead of just combing the web for random things other people have written to strengthen your argument?
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post #7 of 24
6/27/07 at 9:16pm
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Probably used 0.4 dB because of the specific population that he tested. A larger population that perhaps encompassed younger trained people might've eeked that down a bit.

With regards to Chris' comments, I've sent an email over to the author for clarification. I think? he was looking at it from the least signficant bit in those systems.

You could Harrypt, but the wheel doesn't have to be continuously reinvented.
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post #8 of 24
6/28/07 at 8:40pm
Most of that is old news just presented better for the masses. Too bad most if not all snake oil lovers still wont get it. Oh well a fool and his money......
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post #9 of 24
6/29/07 at 7:45am
Quote:
Originally Posted by Chu Gai View Post

Click here.

So....what you're saying is that level matching isn't all that important when comparing components? Hehehehehehe...


Scott
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post #10 of 24
6/29/07 at 8:15am
On the contrary. Level matching is absolutely mandatory in audio subjective tests because most audio qualities are dependent on sound intensity. People tend to choose the audio equipment/device whose volume is higher,
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post #11 of 24
6/29/07 at 8:23am
Quote:
Originally Posted by JorgeLopez11 View Post

On the contrary. Level matching is absolutely mandatory in audio subjective tests because most audio qualities are dependent on sound intensity. People tend to choose the audio equipment/device whose volume is higher,

So if you want a better system, just turn up the volume
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post #12 of 24
6/29/07 at 10:40am
Quote:
Originally Posted by Chu Gai View Post

What Do We Mean By Audible

One thing I've noticed that has a large bearing on our ability to distinguish small changes in volume and tonality is listening in an environment that is free of all early reflections. I've been a professional audio engineer for most of my adult life, and I remember clearly the first time I did a mix after treating all the first reflection points in my studio. All of a sudden I could hear very small changes - definitely less than 0.4 dB - very clearly. Not only changes in volume, but in EQ and effects such as reverb too. I bet if that test were conducted in a reflection free zone (RFZ) that the results would be at least a little different, with more people able to notice finer detail.

--Ethan
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post #13 of 24
6/29/07 at 10:46am
That was an interesting presentation. It would be useful to see the data behind the conclusions and analysis.

The sample size of n=30 stuck out to me.

From the tests and the data, I honestly don't see how the 3rd conclusion was made:

"Audibility is a psychological phenomenon as much or more than a physical one."

A good test for that would have been A & B being exactly the same loudness. How many of the 30 would have answered yes or no? Truly that would help hypothesis test whether loudness is psychological and/or physical.

This definitely got me thinking about something different this morning

- Steve O.
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post #14 of 24
6/29/07 at 10:51am
Thread Starter 
Quote:


So....what you're saying is that level matching isn't all that important when comparing components? Hehehehehehe...


Scott

Exactly Scott! It's important to just play them the way you want, listen to what the salesman says, focus intensely where he wants you to focus, and above all realize that using the right wires, elevation cones or different blocks of wood, replacing good resistors and capacitors with more expensive audiophile versions, is the clue.

Ethan, what do you think of Moulton's comments regarding reflections when it comes to speaker designs?
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post #15 of 24
6/29/07 at 11:18am
Quote:
Originally Posted by Chu Gai View Post

Exactly Scott! It's important to just play them the way you want, listen to what the salesman says, focus intensely where he wants you to focus, and above all realize that using the right wires, elevation cones or different blocks of wood, replacing good resistors and capacitors with more expensive audiophile versions, is the clue.

That's just crazy talk. Besides, everyone knows audio nirvana is all about using the right light switch covers.

But seriously (and just for the record) I do appreciate the need for level matching, but I do find it interesting that the stringency you can achieve may be in excess of what is audible. Also, as Steve O. pointed out, I always think it would be informative to see control data for these sorts of studies to see what the rates of false postives/negatives are.


Scott
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post #16 of 24
6/29/07 at 12:36pm
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Maybe Steve O. will chime in with exactly what he's talking about and in what context.

I think machinadynamica was truly based on the premise of what kind of absolute ridiculousness and bull$hit can I tell and still sell something.
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post #17 of 24
6/29/07 at 1:03pm
Quote:
Originally Posted by Harrypt View Post

Wouldn't it be more interesting to say, oh... set up some tests and do some listening experiments instead of just combing the web for random things other people have written to strengthen your argument?

Do you yourself typically repeat scientific experiments personally, before you accept their results?

In this case the data are saying that a 0.4 dB level difference is probably not audible (especially for musical samples). You have a problem with that? It's not some controversial new findings; it's quite in accord with previous studies of JNDs.
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post #18 of 24
6/29/07 at 1:20pm
Thread Starter 
I made a right triangle with two of the sides being 3" and 4". Should I measure the hypotenuse or just calculate it?
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post #19 of 24
6/29/07 at 4:24pm
Thread Starter 
I asked,
Quote:


On slide 40 of 45 in "What do we mean by audibility" from the Parson's website, it is stated,

In the case of 20-bit vs. 24-bit, the actual change in voltage magnitude is less than 1/10,000th of 1%.

What do you mean by that?

He replied,
Quote:


Thanks for the question!

20 bit yields a ratio of approximately 1:1,000,000, while 24 bit yields a ratio of approximately 1:16,000,000. Assuming that the voltage ratios have a fixed and identical upper value of, say, 1, the 20 bit lower value will be 1:.000001, or 1/10,000th of 1 percent, while the 24 bit value will have a lower value of 1/16th of 1/10,000th of 1 percent, or, slightly less than 1/100,000th of 1 percent.

These are extremely small magnitudes and magnitude changes, and are essentially well below the noise floor of any reasonable audio signal. The actual CHANGE in magnitude will be from, say, 1 millionth of a volt to 1/16 millionth of a volt. Viewed as a percentage change, this will be, by definition, less than the % of signal that the 20 bit signal represents, which is, once again, 1/10,000th of 1%.

This all works out this way because we tie everything to a maximum level of 0 dBFS. All changes in magnitude ratios happen at the vanishingly small end of the range.

I hope this helps. If not, give me a call.

Thanks for writing.

Best,

Dave Moulton
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post #20 of 24
6/29/07 at 6:59pm
Quote:
Originally Posted by krabapple View Post

Do you yourself typically repeat scientific experiments personally, before you accept their results?

In this case the data are saying that a 0.4 dB level difference is probably not audible (especially for musical samples). You have a problem with that? It's not some controversial new findings; it's quite in accord with previous studies of JNDs.

He found a PP presentation on the web and that is scientific proof to you? Laff.
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post #21 of 24
6/29/07 at 10:40pm
And Chu performing and reporting his own test would be better 'proof' to you? Laff.

You're full of it. The real question for people like you is, what proof *would* you accept, that the current scientific consensus on JNDs is correct?
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post #22 of 24
6/29/07 at 11:14pm
People - "audiophiles" included - find it hard to accept scientific results that contradicts cherished beliefs, in particular unsubstantiated ones like astrology or religion.
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post #23 of 24
6/30/07 at 8:47am
Quote:
Originally Posted by Chu Gai View Post

Ethan, what do you think of Moulton's comments regarding reflections when it comes to speaker designs?

Got a link or quote?
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post #24 of 24
6/30/07 at 10:54am
There is a vast body of literature on speech and signal audibility. Our students have a semester long course on audibility theories and their reliability from a psychoacoustic perspective.

It's an extraordinarily complex topic. This presentation did a decent job of talking about JND but it really only pertains to a very small portion of audibility and how it interacts with perception.
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