[LAU] newbie to Linux audio

[Kevin Cosgrove]

On 18 July 2007 at 16:31, "Stuart Allie" <Stuart.Allie at hydro.com.au> wrote:

> That would have been soooooooo much more useful if you had done your
> listening as a double-blind test. 

I still have the DVD-A.

> That is, if you had listened to the
> tracks in a random order and then compared your listening experience to
> the track formats after the fact. 

I suppose we could bring in another party and do just what you say.

> As it is, you could have experienced
> a major case of "confirmation bias".  You were expecting the tracks to
> sound better, and that's exactly what you heard. 

It's hard for me as the subject to say for sure, but I don't think I 
had much bias.  I had a lot of curiosity, not ever hearing the higher 
resolutions before.

> I don't doubt that
> there *was* an audible difference between, say, the mp3 and the 16/44.1
> track, but by not doing a double blind test, your results really aren't
> useful.  Shame about that. 

In my message I gave the qualitative statements.  There were some 
objective measures as well.  For instance, coming back from 24/192 
land into MP3 land, the piano had a distinctive sound of a flanger on 
it, and I'd presume it's artifacts from compressing to MP3.  Between 
16/44.1 and 24/96 details like the rustle of the drummers brushes on 
the snare became apparent, as did the sounds of customers eating at 
tables.  Going from 24/96 to 24/192 the spacial perception improved, 
but the timbre of the instruments didn't change much, if at all.  At 
24/192 more details of customer movements, things like putting on a 
coat, became more identifiable.  For the string quartet, bow noises 
showed up at 24/96, and traffic outside showed up at 24/something.

When we discovered things like this, we went back down the quality 
chain to see where the line of demarcation was between being able to 
hear a feature or not being able to hear it.  That's still not what 
you were after, but it's a bit more objective than my earlier writing.

> I'd love to get hold of that disc and have
> the equipment to listen to it properly.

I got mine for free from Minnetonka.  You might write for one; that's 
what I did.

>  From my reading over the last couple of years what I've learned is that
> the evidence says that:
> - 24 bit sounds better than 16 bit at the same sampling frequency
> because of increased dynamic range

I've read the same, and it's easy to see why.  Especially if music is 
going to be compressed to 16-bit CDs, then starting with greater than 
16 bits seems like a must, or that 16-bit CD will be more like 12-bit
sound (with the number of effective bits being strongly influenced by
the amount & type of compression).

> - 96kHz sounds better than 48/44.1kHZ only when the processing of the
> digital data has introduced aliasing and other artefacts related to the
> sampling frequency.  So 96kHz tracks often *can* sound better than
> 48kHz, but only because of poor processing somewhere along the way.

Don't forget that the whole signal path up to the A/D converter needs 
to be clean (free from noise & distortion as much as possible) or 
whatever "dirt" that exists in the potential bandwidth added by the 
sample rate will be captured, whereas less would be captured at 
44.1kHz.

> - 192kHz is totally unnecessary.

I don't know enough to comment on that.

> Hope that helps somewhat.  Check out Bob Katz's web site and book
> "Mastering Audio" for more that you could ever possibly want to know
> about this stuff :)

I'll add it to my list.  Thanks....
 
--
Kevin