[Pd] OT- FFT and human auditory cortex

Chuckk Hubbard badmuthahubbard at gmail.com
Thu May 25 13:52:31 CEST 2006


On 5/25/06, Charles Henry <czhenry at gmail.com> wrote:
> > > > By phase-locked pulses, do you mean that the hair-cell trigger happens
> > > > at the same point in each cycle, and so the resulting pulses correlate
> > > > to the same phase for each vibration?  If you mean something else,
> > > > it's probably not worth trying to explain.  But please do.
> > >
> yes, I *think* they are phase-locked, meaning that it happens at the
> same phase per oscillation.  I would not know if it is one or two
> action potentials per period or at what point they are triggered, but
> the auto correlation of the auditory nerve bundles shows strong
> correlations at the period of oscillation...implies phase-locked...but
> that's all I got.

Makes sense.  There must be a threshold for how much pressure it takes
to trigger a hair cell, and a steady periodic vibration would tend to
hit that threshold periodically.  I wonder if this has to do with why
certain higher frequencies sound like they are getting higher or lower
as the amplitude changes.  The threshold changes phase or something.

> I'm technically still in school this summer, until I complete a
> literature review for one class.  The topic is neuroscience and
> auditory scene analysis.

Oh yeah, that.

>  I've been way too bogged down in speech
> readings for awhile, and I never liked studying speech much.  I think
> that ASA is about as important of a cognitive psych theory as
> any...This is probably old hat, here, but has anyone read David
> Huron's "Tone and Voice: a derivation of the rules of voice leading
> from perceptual principles" in music perception?  This article got me
> thinking about how voice leading rules and ASA go hand in hand.  Or
> that ASA even subsumes the category of voice leading rules.

Not familiar with ASA or Huron.  I have always found voice leading to
be kind of a boring study, but then it's never been presented to me
with any science, just conventions.


> I talked about it with my advisor, and brought up an interesting idea.
>  The exerimental protocol is just so simple, that we could do it with
> Pd and use only the most elementary objects.  It can be run simply on
> any computer, then, and use Pd to log data to text files.
>
> The big idea is to try to circulate the experiment among Pd users, and
> let them email the data back.  Thus, we could collect a fairly large
> amount of data for an experiment.  Of course, we run into
> institutional issues.  If you wanted the analysis to get published
> somewhere, you'd have to get some kind of approval for the work and
> faces serious issues of reproducibility and lack of controlled
> environment...use headphones (non-standardized) or loudspeakers
> (free-field, room dependent)...a whole lot of experimental design
> problems...

What about keeping the data separate per headphone set?  Then if there
are trends that are consistent between sets, that might be even more
convincing.


>
> I started using Pd, because I had a music composition project
> (going on 2yrs now and still haven't finished) and Max just couldn't
> do what I wanted...I couldn't figure out how to create new externals
>  for Max (probably never tried hard enough), so I switched to Pd.
> The composition project was to create music via stable feedback
> between a loudspeaker and microphone--hence I've tried to build an
> adaptive filter bank for fixing the LS/room/mic response.  I'll get it
>  done one of these days...
>
> Chuck

Sounds pretty creative.  That's something a multimedia major at my
school would do, albeit more involved than they would probably get.
Good luck with it.

-Chuckk




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