Re: By any other name...

[Dan Ellis <dpwe@xxxxxxxxxxxxxxx>]

On 3/22/07, Bruno Repp <repp@xxxxxxxxxxxxxxxx> wrote:
> If objective methods cannot prove the absence of the signal,
> then I would argue that the signal is in fact present. Is an
> objective proof of signal absence typically presented in studies of
> the auditory continuity effect?

I don't think the objective presence or absence is very interesting; there
is a range of circumstances in which a more optimally configured
detector might be able to detect the absence of a perceptually restored
tone (although those circumstances may be surprisingly narrow).

What is more interesting is that even in genuinely undecidable circumstances,
when, as Yokashita puts it, the signal is objectively "either present
or absent",
the perceptual system does not report that ambiguity but instead returns a
confident answer.  Moreover, in the case of continuity, that answer is not the
locally simplest answer (no spectral peaks = no perceived tones), but instead
is the "simplest" answer on a much broader scale (continuous tone more likely
than tone with a gap synchronized with noise burst).

Maybe the objection is that *of course* the perceptual system will do the
reasonable thing of assuming continuity when there is no counter-evidence.
But the computational implementation of a system that can capture and
apply this kind of definition of "reasonableness" is much more complex than
a lay person might expect from the auditory system - and a majore challenge
for those of us interested in modeling perceptual sound analysis.

> If objective methods cannot prove the absence of the signal,
> then I would argue that the signal is in fact present.

This reminds me of the discussion we had a few years ago about the
WW2 aircrews who could conjure up the illusory experience of listening
to favorite pieces of music in among the earsplitting drone of the aircraft
engines during long missions.  Since no objective measure can distinguish
the presence or absence of Beethoven's 5th at 20 dB below the air conditioning
noise in my office, why am I not perceiving it (or only that one, and not the
infinity of other unmeasurably-quiet signals that are also "present")?

 DAn.