[LAU] ABX test invite

[Fons Adriaensen]

On Fri, Apr 05, 2013 at 11:42:31PM +0200, Ralf Mardorf wrote:

> I made many tests not to get knowledge about my abilities, but when we
> developed microphones, or even when we sold stereo pairs, several
> employees listened. Btw. to find a stereo pair it's better to listen,
> than to do measurements! Try to find a stereo pair of microphones that
> fit together, by objective scientific measurements and ask people to
> listen to microphones to find stereo pairs. I'll use the stereo pairs
> from people who listened to the mics, not the pairs that were found by
> objective measurements.

One of the more interesting jobs I've ever done was to define a procedure
to select 4 matching microphone capsules for Ambisonic mics. That's a lot
more difficult than finding good stereo pairs, and you can forget about
doing it by listening. The only thing you could probably achieve that way
is to identify a capsule as completely out of spec and unusable. 
Nor can you do it by *simple* tests, which is maybe the only alternative
to listening you can imagine. It requires, amongst a lot of other things,
comparing directivity factors and phase response over the entire frequency
range, using criteria that are matched to the question to be answered :
can these four mics be used together for an AMB mic or not. It excludes
factors that would easily lead you astray when listening but which are
in the end irrelevant.

> The idea that there is something most near to perfect objectivity is
> a fallacy.

And that statement is completely irrelevant. Nobody (in this context)
claims 'perfect objectivity'. What remains is that a test that at least
tries to exclude subjective factors will be more *reliable* than one
that doesn't. The only purpose of an ABX test is to find out if you can 
tell if X = A or X = B. And the only conclusion taken from that test
(and that conclusion follows logically from it) is that if you can't
do that, it must be very unlikely that you can hear any difference
between A and B. It says nothing about the quality of your ears, your
compentence as a sound engineer, the quality of the recordings, etc.

> Passing a test only will tell us, how good or worse we are in passing
> a test.

Not 'a test' but *that particular test*, which may be highly relevant
even if you prefer not to believe it. 

> Meaningful is the quality of our work and the quality depends to
> the fact on how many different gear in how many different situations
> the sound is good. Is the sound ok in a professional studio and on an
> elCheapo car hifi etc.?

That may be meaningful, but in an entirely different context.

Ciao,


-- 
FA

A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)