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Re: perceptual segregation of sound

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.


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

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.