Re: inharmonic timbres and pitch perception

Hi Paul,

After thinking over what you said again, perhaps I am missing the point?

You are talking about the perceived pitch of a note?

So, though one hears all sorts of inharmonic timbres as well, when
it comes to trying to figure out the pitch of a note heard, the idea
would be that the ear looks for the harmonic series pattern in the
sequence of partials.

Then, the idea would be, if the ear can't find the harmonic series,
it adds in a missing fundamental, somewhere that gives us
an approximation of some sort to the harmonic series.

If that is so, one can then ask if the harmonic
series is the only pattern like this, or if there are other patterns
that can also do the same thing.

How about an experiment, maybe a thought experiment, but possibly one
that could be done in practice too.

Make a timbre which is inharmonic, but with a very strong partial in it, which
one perceives as the pitch of the note.

Play it lots of times at various pitches, until one gets used to it.
Perhaps do that by assigning it to a keyboard and asking someone to
play tunes on it, since when one is using a timbre interactively like
that, one pays more attention to it somehow.

Now, try synthesising it again, and leave out the strong partial that is
usually present, and add, say, a weaker partial an octave below it,
so that one has some cue to lead one to it, (as one has for a bell sound).

Now ask the pitch of various notes played with the new timbre.

Then, find someone else who hasn't heard the first timbre,
and just play them the second timbre with the missing partial.

Do they both give the same results, or does learning the first inharmonic
timbre pre-dispose one to hear the strong partial as the pitch of the
second timbre?

Even if it is just a thought experiment, might help to clarify ideas.

And who knows, just possibly, maybe one could actually do such
an experiment.

Then, my suggestion is that there might be various natural sounds,
not just the harmonic series, but other pitch patterns as well, that
already do do this.

I wonder if you could give that web site ref, I don't think I know
it?

Robert

>I wonder if you could give that web site ref, I don't think I know
>it?

Robert, before you look at my responses below, the web site in question is
http://www.mmk.ei.tum.de/persons/ter.html
<http://www.mmk.ei.tum.de/persons/ter.html> ; scroll down to Perception of
Auditory Pitch, and read all the articles linked to below it.

Also I'd recommend strongly you find Pierce's book _Science and Musical
Sound_. Go to a library and read the chapters "Helmholtz and Consonance" and
then "Rameau and Harmony".

>Make a timbre which is inharmonic, but with a very strong >partial in it,
which
>one perceives as the pitch of the note.

The magic of harmonic timbres is that one perceives a pitch even though
there isn't one very strong partial -- and the pitch of the timbre might not
even correspond to _any_ of the partials. The less the partials correspond
to a harmonic series, the less certain you'll be as to what pitch you're
perceiving.

Yes, there are lots of percussion instruments that have a pretty clear
pitch, at least clearly classifiable in terms of position in a given scale.
But the spectrum there is usually just like white noise through a band-pass
filter. All the energy of the sound is in a very narrow frequency range.
This is very different from the situation in which you have an inharmonic
timbre and used the intervals among the partials are used to construct
chords, etc.

But let's keep going with your example. Basically, since one partial is loud
enough to be perceives as the pitch, and the timbre is inharmonic, the other
partials are just perceived as a kind of added noise and don't contribute to
the perception of the pitch of the timbre.

>Play it lots of times at various pitches, until one gets used to it.
>Perhaps do that by assigning it to a keyboard and asking someone to
>play tunes on it, since when one is using a timbre interactively like
>that, one pays more attention to it somehow.

>Now, try synthesising it again, and leave out the strong partial that is
>usually present, and add, say, a weaker partial an octave below it,
>so that one has some cue to lead one to it, (as one has for a bell sound).

I don't understand what the analogy is with the bell sound at all.

But overall, sounds like a very interesting line of thought toward some
fascinating experimental investigations, Robert!