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Results for 24bit/96KHz test, vs. 16bit/44.1KHz
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post Jan 4 2004, 06:20
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I've been trying tigre's 24/96 test proposed in this thread, and also discussed at Afterdawn.

High definition stuff is also discussed here, here, and samples are here, but yeah, we've got a listening test thread now, so might as well use it...

My equipment is an M-Audio Revolution 7.1 feeding straight to Sennheiser HD 200 headphones. I downloaded Lovely_1.wv and used foobar2000 to do resampling, replaygaining, and ABXing. At first I was using waveOut, but then I retested them all using Kernel Streaming.

Anyway, I can ABX (with less than 1% chance of guessing):

[24/96] vs. [24/96->16/44.1->24/96] (slow resampling, dither)
[24/96] vs. [24/96->24/44.1->24/96] (slow resampling)
[24/96] vs. [24/96->16/96->24/96] (dither)

My results varied a bit, but all were significant. The first test I did, I was not expecting to hear any difference, so I was very careful, and got 12/12. Since then I've had 12/12s, 11/12s, a 10/10, and an 8/8 (got interrupted but still a valid result, and it was only a retest...)

The most consistently hearable difference for me is when I listen between 5.2 and 7.2 seconds. Some sort of drum gets hit at about 5.7s. The high definition one is somehow more convincing. Today I was thinking of the good one as a push and the bad one as a pull, but yeah that's not a very helpdul description..

I'm also hearing other differences, but it's hard to know whether I'm being tipped off by something while focussing on something else, or even what the actual difference is in objective terms.

So, what could be wrong? What else would be worth testing? I was thinking of noise shaping the output maybe...
I'm not that keen to do a huge amount of retesting with every possible combination, but if someone thinks of something important I'll be sure to check it.
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Pio2001
post Jul 2 2004, 22:01
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In French, a positive ABX result between castanet2-1644.wav and castanets2-2496.wav from the PCABX samples, by GBo :

http://www.homecinema-fr.com/forum/viewtop...76126#168172020

ABX 11/12

Beware of the slippery snake oil everywhere else in that forum.
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WmAx
post Jul 26 2004, 18:55
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I can not read French and a translator makes a mess.

Taking into account the known IM problems with a single transducer attempting to cover both sonic and ultrasonic ranges -- I wonder the point at all of this ABX test -- when performed with hardware that may cause audible artifacts not directly relevant to the intention of the test(audibility of bandwidth variable only). I believe controls on the actual audio performance need to be established at this point.

ALternative: Someone assembles a special headphone(as someone suggested earlier in the thread) using a normal band and ultrasonic band driver element, amplilified by two seperate amplifiers and an active crossover circuitry. A 24/96 USB sound device could be picked, tested and confirmed to function adequately for the test. After complete system is tested for properly operation -- This system could be shipped between test subjects: they only need plug in the USB device, install software/samples/drivers and proceed to perform the ABX test using their computer.

Feasibility?

-Chris

QUOTE (Pio2001 @ Jul 2 2004, 01:01 PM)
In French, a positive ABX result between castanet2-1644.wav and castanets2-2496.wav from the PCABX samples, by GBo :

http://www.homecinema-fr.com/forum/viewtop...76126#168172020

ABX 11/12

Beware of the slippery snake oil everywhere else in that forum.
*


This post has been edited by WmAx: Jul 26 2004, 18:55
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Pio2001
post Jul 26 2004, 21:09
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QUOTE (WmAx @ Jul 26 2004, 06:55 PM)
Taking into account the known IM problems with a single transducer attempting to cover both sonic and ultrasonic ranges -- I wonder the point at all of this ABX test -- when performed with hardware that may cause audible artifacts not directly relevant to the intention of the test(audibility of bandwidth variable only). I believe controls on the actual audio performance need to be established at this point.


I agree with you. If we want to prove that ultrasonic frequencies can have an audible effect, we need bi-amplification, or another way to get rid of IMD.
However, ABX success seem to show that after all, there might be an audible difference between a 44.1/16 bits recording and a 96/24 bits one, whatever causes this.

QUOTE (WmAx @ Jul 26 2004, 06:55 PM)
ALternative: Someone assembles a special headphone(as someone suggested earlier in the thread) using a normal band and ultrasonic band driver element, amplilified by two seperate amplifiers and an active crossover circuitry.


This seems out of reach, unless you have the money and time to make the headphones.
It is not difficult to set two speakers in one headphones. It was already done with the Superex PRo-B VI, for example. The passive filter was inside the shells (and the headphones weighted 480 g !). But the frequency junction between the drivers had a wavelenght larger that the size of the tweeter, which allowed to play the bass around it in a coaxial way in front of the ear. Maybe trying to set a super tweeter in the middle of headphones, and still try to reproduce high frequencies up to 18 kHz from another driver behind it would lead to big problems.
Also, it will become difficult to check with a microphone that there is no intermodulation at the output. One would have to use an artificial head to record the sound.
Once done, we still need to find some people willing to pass the test (but if you have the money to build the headphones, it should not cost much more to pay people for undergoing the test).

Anyway, I think we should investigate a completely different field first. The matter of ultrasonic frequencies has very little impact in my opinion, since most speakers and headphones can't play them anyway ! What's the use of extending SACD's response to 100 kHz while only plasma tweeters can reach this frequency ?
In that french forum, sort of an elite audiophile one, the discussion about high definition formats quickly took an interesting way : people agreed (though without any proper listening tests) that the main problem should not be the reproduction of high frequencies, but the audibility of the antialias filters.
They gave the example of HDCD. According to them, the HDCD information tells the DAC which filter to use in order to perform first order oversampling. This is true, the docs at http://www.hdcd.com confirms it.
I couldn't verify it but it seems very plausible, HDCD would use a steep filter when the music has much high frequency content, in order to preserve it, and a soft filter when music has much transients, in order to avoid ringing, and keep temporal accuracy.
If this is founded, the improvements given by high definition formats would be to simply get rid of the limitations of these two kinds of filters. A 24 bits 96 kHz PCM stream has a linear frequency response much above 20 kHz, and is free of ringing in the audio band.

We should first check if this is audible, which would confirm the superiority of DVD-A and maybe SACD over the audio CD, which suffers either from ringing either from reduces bandwidth, and check also if 48 kHz 24 bits would not be enough to solve all problems if they exist, which would show that SACD and DVD-A are nonetheless overkill.

The most direct way would be to use a high end audiophile DAC which gives the choice between different antialias filters. Some models do it.

Unfortunately, I don't plan to do it in the near future, because I don't have such a DAC, nor the money to buy one.
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WmAx
post Jul 26 2004, 21:33
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QUOTE
I agree with you. If we want to prove that ultrasonic frequencies can have an audible effect, we need bi-amplification, or another way to get rid of IMD.
However, ABX success seem to show that after all, there might be an audible difference between a 44.1/16 bits recording and a 96/24 bits one, whatever causes this.


Yes, 'A' difference. I am not yet comfortable attribuitng this to the bandwidth -- I agree that other indirect issues are probably responsible.

QUOTE
This seems out of reach, unless you have the money and time to make the headphones.


I do not have access to the required headphone testing heads in order to do proper/consistent measurments of headphones. 2nd, the cost of the testing rig would be of concern -- I would not be comfortable purchasing these materials then shipping them to unknown people.


QUOTE
Anyway, I think we should investigate a completely different field first. The matter of ultrasonic frequencies has very little impact in my opinion, since most speakers and headphones can't play them anyway ! What's the use of extending SACD's response to 100 kHz while only plasma tweeters can reach this frequency ?
In that french forum, sort of an elite audiophile one, the discussion about high definition formats quickly took an interesting way : people agreed (though without any proper listening tests) that the main problem should not be the reproduction of high frequencies, but the audibility of the antialias filters.


Audibility testing has been performed on anti-alias filters:

Perception of Phase Distortion in Anti-Alias Filters

AES Preprint Number: 2008 Convention: 74 (September 1983)
Authors: Preis, D.; Bloom, P. J.

EDIT: It should be noted that the above perceptual testing paper specifically dicusses an audibility test performed using pulsed test signals played over headphones. Pio, If you want a copy of the paper, e-mail me: wmax@linaeum.com

-Chris

This post has been edited by WmAx: Jul 26 2004, 22:06
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krabapple
post Aug 20 2004, 07:27
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I'd be curious to know the conclusions of that 1983 AES paper.

Also, if we consider the hypothesis that it's tha antialiasing filters that are audible,
would this be considered an intrinsic audible difference between Redbook 16/44 and higher-rez formats, or would it be considered an implementation issue? In other words, is it *inevitable* that 16/44 must employ audible antialiasing or is the putative problem separable from the format?
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WmAx
post Aug 20 2004, 18:47
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QUOTE (krabapple @ Aug 20 2004, 01:27 AM)
I'd be curious to know the conclusions of that 1983 AES paper.

Also, if we consider the hypothesis that it's tha antialiasing filters that are audible,
would this be considered an intrinsic audible difference between Redbook 16/44 and higher-rez formats, or would it be considered an implementation issue?  In other words, is it *inevitable* that 16/44 must employ audible antialiasing or is the putative problem separable from the format?
*


I'm not aware of anyone demonstrating under properly controlled conditions, that a properly used anti-alias with filter as is required on 44.1kHz, has any audible effect for humans.

-Chris

This post has been edited by WmAx: Aug 20 2004, 18:47
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Posts in this topic
- listen   Results for 24bit/96KHz test   Jan 4 2004, 06:20
- - tigre   Thanks for the effort, listen. I hope this will en...   Jan 4 2004, 18:53
- - listen   I just tried another ABX test. This time it was 9...   Jan 5 2004, 08:11
- - tigre   Intreseting. Mabe we're getting closer to trac...   Jan 5 2004, 13:11
- - listen   Hi tigre, I'm not sure why I didn't check ...   Jan 6 2004, 07:48
- - KikeG   Such rate of success in ABX makes the results a li...   Jan 6 2004, 16:22
- - KikeG   Ok, finally I got to generate the test files. Dow...   Jan 7 2004, 10:52
- - 2Bdecided   QUOTE (KikeG @ Jan 7 2004, 09:52 AM)Don't...   Jan 7 2004, 11:26
- - KikeG   Now, when you have tried the test files at my prev...   Jan 7 2004, 12:06
- - listen   Thanks for the input, I'll start working throu...   Jan 7 2004, 23:49
- - Pio2001   I tried to ABX KikeG's files : lovely_short vs...   Jan 9 2004, 00:31
- - listen   Ok, I had a session last night and got some result...   Jan 9 2004, 02:13
- - Pio2001   My soundcard doesn't support kernel streaming....   Jan 9 2004, 12:22
- - Continuum   OT: QUOTE (Pio2001 @ Jan 9 2004, 12:31 AM)......   Jan 9 2004, 14:59
- - KikeG   Very interesting... Listen, could you try another...   Jan 10 2004, 12:25
- - Garf   QUOTE (listen @ Jan 9 2004, 03:13 AM)lovely_d...   Jan 10 2004, 12:47
- - listen   Sure I will try the next batch, and double check f...   Jan 11 2004, 00:57
- - Continuum   QUOTE (listen @ Jan 11 2004, 12:57 AM)the dif...   Jan 11 2004, 08:43
- - Garf   QUOTE (Continuum @ Jan 11 2004, 09:43 AM)If y...   Jan 11 2004, 10:51
- - Continuum   QUOTE (Garf @ Jan 11 2004, 10:51 AM)Another p...   Jan 11 2004, 11:35
- - Garf   Some more stuff to test with: http://sjeng.org/ft...   Jan 11 2004, 14:02
- - listen   Just thought I should say that I'm leaving tow...   Jan 14 2004, 03:38
- - listen   I got motivated by a thread I saw the other day......   Mar 31 2004, 04:57
- - tigre   listen, thanks for still spending time on this. T...   Mar 31 2004, 08:39
- - tigre   QUOTE (listen @ Mar 31 2004, 05:57 AM)I had a...   Mar 31 2004, 08:47
- - 2Bdecided   QUOTE (listen @ Jan 10 2004, 11:57 PM)About v...   Mar 31 2004, 10:51
- - phwip   Please forgive my ignorance as a complete newbie t...   Mar 31 2004, 11:40
- - listen   Well yes you pretty much sum it up perfectly in my...   Mar 31 2004, 12:36
- - tigre   phwip: immagine you throw a coin 10 times. The pro...   Mar 31 2004, 14:12
- - tigre   QUOTE (listen @ Mar 31 2004, 01:36 PM)Well ye...   Mar 31 2004, 14:22
- - sshd   I hate statistics: The probability to get 11 corr...   Mar 31 2004, 14:33
- - Pio2001   It is perfectly valid, and recommended, to train o...   Mar 31 2004, 19:39
- - phwip   Thanks Pio2001, that makes things much clearer for...   Mar 31 2004, 22:23
- - listen   I've got a master volume, and also faders for ...   Mar 31 2004, 22:44
- - listen   Thanks for the stats sshd.. QUOTE (sshd @ Mar...   Apr 1 2004, 05:39
- - KikeG   Ok, I've been quite absent from some time here...   Apr 2 2004, 16:40
- - tigre   Thanks for your answer, KikeG. I've been think...   Apr 2 2004, 18:08
- - Pio2001   When you add two sinusoides of different frequenci...   Apr 2 2004, 20:56
- - listen   Hi tigre.. I don't have a separate headphone a...   Apr 3 2004, 01:38
- - listen   Well, if the difference frequencies appear mostly ...   Apr 6 2004, 02:49
- - Pio2001   What do you mean ? If the 4 kHz frequency of our e...   Apr 6 2004, 11:47
- - listen   Oh. . No, I was thinking of KikeG's speculati...   Apr 14 2004, 23:31
- - listen   Well.. I've been busy again, but I see I haven...   May 13 2004, 07:30
- - listen   I thought I should clarify this 'result pickin...   May 14 2004, 02:11
- - Pio2001   It's been a long time since I read this thread...   May 14 2004, 11:18
- - listen   So, quite sincerely, if my Sennheiser's are no...   May 20 2004, 12:50
- - Pio2001   I don't know, but for me, it was not a waste o...   May 20 2004, 16:09
- - WmAx   QUOTE (Pio2001 @ May 20 2004, 07:09 AM)I don...   Jun 1 2004, 16:00
- - Pio2001   Thank you for the link, WmAx, Very interesting. I...   Jun 2 2004, 01:11
- - WmAx   QUOTE (Pio2001 @ Jun 1 2004, 04:11 PM)Thank y...   Jun 2 2004, 01:52
- - Pio2001   QUOTE (WmAx @ Jun 2 2004, 01:52 AM)A signfica...   Jun 7 2004, 20:43
- - WmAx   QUOTE (Pio2001 @ Jun 7 2004, 11:43 AM)[ QUOTE...   Jun 7 2004, 22:22
- - Pio2001   QUOTE (WmAx @ Jun 7 2004, 10:22 PM)Thank you ...   Jun 7 2004, 23:06
- - Pio2001   In French, a positive ABX result between castanet2...   Jul 2 2004, 22:01
|- - WmAx   I can not read French and a translator makes a mes...   Jul 26 2004, 18:55
|- - Pio2001   QUOTE (WmAx @ Jul 26 2004, 06:55 PM)Taking in...   Jul 26 2004, 21:09
|- - WmAx   QUOTE I agree with you. If we want to prove that u...   Jul 26 2004, 21:33
|- - krabapple   I'd be curious to know the conclusions of that...   Aug 20 2004, 07:27
|- - WmAx   QUOTE (krabapple @ Aug 20 2004, 01:27 AM)I...   Aug 20 2004, 18:47
- - Pio2001   I didn't have the time yet to read all this pa...   Aug 20 2004, 12:14
|- - WmAx   QUOTE (Pio2001 @ Aug 20 2004, 06:14 AM)I didn...   Aug 20 2004, 18:33
- - unfortunateson   I created a 96khz sample (a bad electric guitar do...   Apr 16 2008, 06:02
- - Axon   Interesting. How did you downsample it?   Apr 16 2008, 07:02
|- - unfortunateson   QUOTE (Axon @ Apr 15 2008, 23:02) Interes...   Apr 16 2008, 07:23
- - unfortunateson   QUOTE (unfortunateson @ Apr 15 2008, 22:0...   Apr 17 2008, 22:55
- - unfortunateson   ABX log for 96khz vs 44.1khz resample (r8brain res...   Apr 18 2008, 03:47
|- - user   You have compared 96-24 vs. 44.1-16. There were ch...   Apr 18 2008, 12:55
|- - unfortunateson   QUOTE (user @ Apr 18 2008, 04:55) You hav...   Apr 18 2008, 16:19
|- - Nick.C   QUOTE (unfortunateson @ Apr 18 2008, 16:1...   Apr 18 2008, 16:28
- - MLXXX   I assumed Unfortunateson had left the material at ...   Apr 18 2008, 15:11
|- - user   Hi MLXXX, can you also test some other ABX, with ...   Apr 18 2008, 16:11
- - MLXXX   Hi user, I had no desire to introduce an additiona...   Apr 18 2008, 16:36


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