Re: perceptual segregation of sound

[John Bates <jkbates@xxxxxxxxxxx>]

This note was intended to be sent to the entire list (my change of 
e-mail address prevented it from appearing); Dan has replied to me privately.

Dan,

What you've suggested so succinctly seems a lot like the concepts on 
perception that I discuss on my Web site. Using a basic system 
analysis approach I've tried to find fundamental principles from 
which to establish generalized requirements for sensory systems based 
on what it takes for animals to survive in their environments.

Here is some of my thinking: Survival requires an animal's sensory 
organs to produce a timely response to environmental information. 
These responses must identify the relative importance of sources in a 
way that describes a "situation" whereby  "awareness" characterizes 
the auditory scene.  In any situation, sensors should be able to 
select for attention instantaneously the single most important source 
within the scene. To do this the model I propose has a hierarchy of 
perceptual levels each of which has its own ability for awareness and 
attention but is subservient to judgments by higher authority. Each 
level's responses are based upon specific time frames within which 
information from each level can be made available. (Simple meanings 
occupy less time to absorb than complicated meanings,) In addition, 
each level is capable of selecting a priority source within its 
domain for attention. For example, the lowest levels which have the 
simplest information could respond reflexively to a source within 
milliseconds. But its response could be moderated by a top-down 
decision from higher levels. It is thus possible, as you suggest, 
that what seems like simultaneous multiple-source attention at the 
conscious level is actually the rapid switching of priorities among 
source objects based on subliminal decisions at the lower levels. As 
an example, consider the complexity of the attention decisions a 
quarterback must process within the few seconds he has during a football play.

A crucial question: how to achieve and synchronize timely responses 
at all levels. It appears to me that this problem has not been 
seriously addressed in the current paradigm.

John Bates
 <http://home.computer.net/~jkbates>

At 12:18 PM 4/28/06, you wrote:

I think another factor to consider in the concurrent segregation of 
sounds is that much of the segregation may be accomplished 
pre-attentively.  Low-level (in the brain, and even cochlea) feature 
detectors may segregate aspects of sounds, if not the sounds 
themselves, well before they percolate up to what we call 
"consciousness."  This would depend on the type of segregating cue 
under consideration, whether it is pitch, spatial location, onset time, etc.