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ABX question - Arny K

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Anonymous
July 25, 2004 7:51:26 PM

Archived from groups: rec.audio.tech (More info?)

To Arny,

I get significant p-values (<0.05, n=100) when I test the samples
16/44.1 vs 16/38 downsampled triangle. Is that a common observation? I
only use cheap headphones, but there is a slight noticable difference
in the attack rate of the triangle. However, I can only faintly hear
18 kHz, nothing at 19 kHz for static tones.

Or perhaps there is some malfunction of the ABX software for mac? I
did not expect to get this value, but I will repeat this again.


T

More about : abx question arny

Anonymous
July 26, 2004 12:31:16 AM

Archived from groups: rec.audio.tech (More info?)

"Thomas A" <Thomas_Akerlund@hotmail.com> wrote in message
news:9a6b3d08.0407251451.414e511f@posting.google.com

> I get significant p-values (<0.05, n=100) when I test the samples
> 16/44.1 vs 16/38 downsampled triangle. Is that a common observation?

First positive report I've ever heard of.

>I only use cheap headphones, but there is a slight noticable difference
> in the attack rate of the triangle. However, I can only faintly hear
> 18 kHz, nothing at 19 kHz for static tones.

Your playback system may have nonlinear distortion that intermodates content
> 19 KHz down into lower frequencies.

> Or perhaps there is some malfunction of the ABX software for mac? I
> did not expect to get this value, but I will repeat this again.

Try a better playback system (especially your audio interface on the Mac)
and see what happens.
Anonymous
July 26, 2004 6:25:15 AM

Archived from groups: rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in message news:<Y-adnSrliK9RzZncRVn-pg@comcast.com>...
> "Thomas A" <Thomas_Akerlund@hotmail.com> wrote in message
> news:9a6b3d08.0407251451.414e511f@posting.google.com
>
> > I get significant p-values (<0.05, n=100) when I test the samples
> > 16/44.1 vs 16/38 downsampled triangle. Is that a common observation?
>
> First positive report I've ever heard of.

How about the 16/32? I started with this test to figure out what to
listen for. How are other people hearing this?
>
> >I only use cheap headphones, but there is a slight noticable difference
> > in the attack rate of the triangle. However, I can only faintly hear
> > 18 kHz, nothing at 19 kHz for static tones.
>
> Your playback system may have nonlinear distortion that intermodates content
> > 19 KHz down into lower frequencies.

Yes, agreed.
>
> > Or perhaps there is some malfunction of the ABX software for mac? I
> > did not expect to get this value, but I will repeat this again.
>
> Try a better playback system (especially your audio interface on the Mac)
> and see what happens.

I am going to buy the M-audio transit, and try it out. It measures ok,
I guess:

http://www.fixup.net/products/benchmarks/Transit1644.ht...
Related resources
Anonymous
July 26, 2004 7:14:31 AM

Archived from groups: rec.audio.tech (More info?)

On 25 Jul 2004 15:51:26 -0700, Thomas_Akerlund@hotmail.com (Thomas A)
wrote:

>To Arny,
>
>I get significant p-values (<0.05, n=100) when I test the samples
>16/44.1 vs 16/38 downsampled triangle. Is that a common observation? I
>only use cheap headphones, but there is a slight noticable difference
>in the attack rate of the triangle. However, I can only faintly hear
>18 kHz, nothing at 19 kHz for static tones.
>
>Or perhaps there is some malfunction of the ABX software for mac? I
>did not expect to get this value, but I will repeat this again.
>
>
>T

If you are monitoring your progress as you go (able to see whether
each trial is correct or not), then the ability to stop whenever p
dips below 0.05 constitutes a form of "cherry picking." As the number
of trials increases in such a test (termed a sequential test), the
probability of being able to cherry pick at p < 0.05 increases
greatly.

If you fixed the number of trials prior to starting, and then
continued until you reached this pre-determined n, then your test is
(statistically) valid.

ff123
Anonymous
July 26, 2004 7:46:54 AM

Archived from groups: rec.audio.tech (More info?)

ff123 <ff123@noneya.org> wrote in message news:<vit8g05kr17asvo58hd1t8rsm0l5n0n3p7@4ax.com>...
> On 25 Jul 2004 15:51:26 -0700, Thomas_Akerlund@hotmail.com (Thomas A)
> wrote:
>
> >To Arny,
> >
> >I get significant p-values (<0.05, n=100) when I test the samples
> >16/44.1 vs 16/38 downsampled triangle. Is that a common observation? I
> >only use cheap headphones, but there is a slight noticable difference
> >in the attack rate of the triangle. However, I can only faintly hear
> >18 kHz, nothing at 19 kHz for static tones.
> >
> >Or perhaps there is some malfunction of the ABX software for mac? I
> >did not expect to get this value, but I will repeat this again.
> >
> >
> >T
>
> If you are monitoring your progress as you go (able to see whether
> each trial is correct or not), then the ability to stop whenever p
> dips below 0.05 constitutes a form of "cherry picking." As the number
> of trials increases in such a test (termed a sequential test), the
> probability of being able to cherry pick at p < 0.05 increases
> greatly.
>
> If you fixed the number of trials prior to starting, and then
> continued until you reached this pre-determined n, then your test is
> (statistically) valid.
>
> ff123

Determined n=100. One trial, after I going from 16/32 excercise. But
it still can be intermod. distorsion.

T
Anonymous
July 26, 2004 10:05:55 AM

Archived from groups: rec.audio.tech (More info?)

"Thomas A" <Thomas_Akerlund@hotmail.com> wrote in message
news:9a6b3d08.0407260125.65e33d78@posting.google.com
> "Arny Krueger" <arnyk@hotpop.com> wrote in message
> news:<Y-adnSrliK9RzZncRVn-pg@comcast.com>...
>> "Thomas A" <Thomas_Akerlund@hotmail.com> wrote in message
>> news:9a6b3d08.0407251451.414e511f@posting.google.com
>>
>>> I get significant p-values (<0.05, n=100) when I test the samples
>>> 16/44.1 vs 16/38 downsampled triangle. Is that a common observation?
>>
>> First positive report I've ever heard of.
>
> How about the 16/32? I started with this test to figure out what to
> listen for. How are other people hearing this?

They hear it as sounding the same as the reference.

>>> I only use cheap headphones, but there is a slight noticable
>>> difference in the attack rate of the triangle. However, I can only
>>> faintly hear 18 kHz, nothing at 19 kHz for static tones.
>>
>> Your playback system may have nonlinear distortion that intermodates
>> content
>>> 19 KHz down into lower frequencies.

> Yes, agreed.

In days of yore, a sound card called the PAS-16 that did this.

>>> Or perhaps there is some malfunction of the ABX software for mac? I
>>> did not expect to get this value, but I will repeat this again.
>>
>> Try a better playback system (especially your audio interface on the
>> Mac) and see what happens.

> I am going to buy the M-audio transit, and try it out. It measures ok,
> I guess:

> http://www.fixup.net/products/benchmarks/Transit1644.ht...

Yes, that looks pretty good. The problem with USB 1.1 has always been a
tendency towards clicks and pops on some machines.
Anonymous
July 26, 2004 10:41:31 AM

Archived from groups: rec.audio.tech (More info?)

"Arny Krueger" <arnyk@hotpop.com> wrote in message news:<Y-adnSrliK9RzZncRVn-pg@comcast.com>...
> "Thomas A" <Thomas_Akerlund@hotmail.com> wrote in message
> news:9a6b3d08.0407251451.414e511f@posting.google.com
>
> > I get significant p-values (<0.05, n=100) when I test the samples
> > 16/44.1 vs 16/38 downsampled triangle. Is that a common observation?
>
> First positive report I've ever heard of.
>
> >I only use cheap headphones, but there is a slight noticable difference
> > in the attack rate of the triangle. However, I can only faintly hear
> > 18 kHz, nothing at 19 kHz for static tones.
>
> Your playback system may have nonlinear distortion that intermodates content
> > 19 KHz down into lower frequencies.
>
> > Or perhaps there is some malfunction of the ABX software for mac? I
> > did not expect to get this value, but I will repeat this again.
>
> Try a better playback system (especially your audio interface on the Mac)
> and see what happens.

I remade a test today quite sloppy (I was in a hurry doing other
things) with better headphones using the 16/32 vs 16/44.1 and decided
for n=50. I got 35/50, p<0.05. What has people reported with 16/32?

When I get the USB soundcard later this week I will give another
report. Probably the audible phenomenon dissappears. :) 

T
Anonymous
July 26, 2004 2:06:14 PM

Archived from groups: rec.audio.tech (More info?)

"Thomas A" <Thomas_Akerlund@hotmail.com> wrote in message
news:9a6b3d08.0407260541.72ab606e@posting.google.com
> "Arny Krueger" <arnyk@hotpop.com> wrote in message
> news:<Y-adnSrliK9RzZncRVn-pg@comcast.com>...
>> "Thomas A" <Thomas_Akerlund@hotmail.com> wrote in message
>> news:9a6b3d08.0407251451.414e511f@posting.google.com
>>
>>> I get significant p-values (<0.05, n=100) when I test the samples
>>> 16/44.1 vs 16/38 downsampled triangle. Is that a common observation?
>>
>> First positive report I've ever heard of.
>>
>>> I only use cheap headphones, but there is a slight noticable
>>> difference in the attack rate of the triangle. However, I can only
>>> faintly hear 18 kHz, nothing at 19 kHz for static tones.
>>
>> Your playback system may have nonlinear distortion that intermodates
>> content
>>> 19 KHz down into lower frequencies.
>>
>>> Or perhaps there is some malfunction of the ABX software for mac? I
>>> did not expect to get this value, but I will repeat this again.
>>
>> Try a better playback system (especially your audio interface on the
>> Mac) and see what happens.
>
> I remade a test today quite sloppy (I was in a hurry doing other
> things) with better headphones using the 16/32 vs 16/44.1 and decided
> for n=50. I got 35/50, p<0.05. What has people reported with 16/32?

Again, very little. There's a reason why the 28 and 22 KHz SR samples are
provided. ;-)

> When I get the USB soundcard later this week I will give another
> report. Probably the audible phenomenon dissappears. :) 

Wating on the proverbial pins and needles.
Anonymous
July 26, 2004 8:31:26 PM

Archived from groups: rec.audio.tech (More info?)

Thomas A wrote:
> To Arny,
>
> I get significant p-values (<0.05, n=100) when I test the samples
> 16/44.1 vs 16/38 downsampled triangle. Is that a common observation? I
> only use cheap headphones, but there is a slight noticable difference
> in the attack rate of the triangle. However, I can only faintly hear
> 18 kHz, nothing at 19 kHz for static tones.
>
> Or perhaps there is some malfunction of the ABX software for mac? I
> did not expect to get this value, but I will repeat this again.

You sure you can hear 18KHz - not intermod products ? You must be very
young.....


geoff
Anonymous
July 26, 2004 8:31:27 PM

Archived from groups: rec.audio.tech (More info?)

"Geoff Wood" <geoff@paf.co.nz-nospam> wrote in message news:<_O%Mc.336$zS6.53287@news02.tsnz.net>...
> Thomas A wrote:
> > To Arny,
> >
> > I get significant p-values (<0.05, n=100) when I test the samples
> > 16/44.1 vs 16/38 downsampled triangle. Is that a common observation? I
> > only use cheap headphones, but there is a slight noticable difference
> > in the attack rate of the triangle. However, I can only faintly hear
> > 18 kHz, nothing at 19 kHz for static tones.
> >
> > Or perhaps there is some malfunction of the ABX software for mac? I
> > did not expect to get this value, but I will repeat this again.
>
> You sure you can hear 18KHz - not intermod products ? You must be very
> young.....
>
>
> geoff

That is from my speakers and test CD, not from computer. Depends of
course of SPL, don't remember now what I used. 17 kHz is fine. 18 kHz
is well, very faint. 19 kHz is nothing. I am not very young, but that
is a relative term. :) 
!