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Re: Pitch in a non-animate world

Dear Christian and list,

I completely agree with you.  Like you, I have noticed the fact that in the
natural environment in which our ancestors evolved (no machines or other
human artifacts), almost all periodic sounds are from animals.  The
exception might be wind whistling through tree branches, or the examples
you cited.

I also agree with you that it is likely that many of the behaviors that
produce such sounds co-evolved with communication and served that function
from early on -- I am thinking, for example, of the mating calls of
crickets.   Of course, this evolution for sonic communication went along
with the evolution of visual communication (e.g., the color patterns in
squids, or the mating displays of birds and possibly of earlier dinosaurs,
or the displays of mammals such as the size of the antlers of deer),
chemical communication  (insects, scents of mammals in heat), and tactile
communication (e.g., in the communication between a mammalian mother and
her nursing infants).

Auditory communication has a number of advantages over these other forms.
As opposed to visual communication, it passes around interposed objects,
such as trees or rocks, retaining most of the important information
(except, sometimes, for place of origin).  At low frequencies, such as
those used by elephants, it can be heard very far away.  As opposed to
tactile communication, it works even when the animals aren't in proximity.
As opposed to chemical communication carried by scent, it is capable of
forming rapidly changing temporal patterns.  These unique capabilities of
sound have probably affected the way in which its use has evolved.

The advantage of the use of pitch in communication is the very fact that it
is not likely to have arisen accidentally from non-communicative events; so
a pitch implies a communicative event -- not necessarily one involving your
own species.  So recognition processes would have to sort them out.  Of
course, for any animal of even modest intelligence, the recognition that
another species (predator or prey) is communicating close to you can also
have vital significance.



Albert S. Bregman, Emeritus Professor
Psychology Dept., McGill University
1205 Docteur Penfield Avenue
Montreal, Quebec
Canada  H3A 1B1

     Voice: +1 (514) 398-6103
     Fax:     +1 (514) 398-4896

 ----- Original Message -----
From: "Christian Kaernbach" <auditory@xxxxxxxxxxxx>
To: <AUDITORY@xxxxxxxxxxxxxxx>
Sent: Wednesday, March 02, 2005 1:08 PM
Subject: Pitch in a non-animate world

> Dear List,
> It recently came to my mind that nearly all experiences of pitch are
> related to animal communication soounds. Sure, there is something like
> edge pitch of broadband stimuli, maybe even echo pitch under specific
> conditions, but clearly periodic sounds stemming from a periodically
> moving source would nearly always come from an animal (and most often be
> communication sounds... exception: humming of bees etc.). Is this a
> complete nonsense? Or could it be that pitch processing evolved in
> parallel to communication capabilities?
> Best,
> Christian Kaernbach