Re: spatial separation and ASA

[Al Bregman <bregman@xxxxxxxxxxxxxxxxxxxx>]

Dear List,

In reply to Pierre Divenyi and others, perhaps we should not be
quite so pessimistic about the role of spatial separation in
allowing signals to be segregated.  It is true that laboratory
studies such as Pierre's have shown that when fairly steady
signals have to be segregated by place alone, performance is not
very good.  But in a natural environment, it would be unlikely
that sounds at different locations would be so similar or so
steady.  The role of spatial cues in segregation may be to
enhance the segregation based on other factors.  In other words,
in cases where two signals were partially segregated by factor X,
adding a difference in location would strengthen the segregation.
A good example might be where X stands for independent patterns
of amplitude fluctuation.  These fluctuations would provide
instants at which better independent spatial estimates could be
made.  Stringing similar spatial estimates together sequentially,
along with the spectrum of the signal at those instants might
give a clearer picture of the two sounds.  (We know that spatial
differences do play an important role in SEQUENTIAL grouping.).
A similar argument could be made for cases in for other

The idea that spatial information does make a substantial
contribution to segregation -- under conditions where the sounds
also differ in respects other than spatial -- may explain why
stereophonic recordings allow a clearer perception of the
individual instruments (or groups of instruments) than monophonic
recordings do.

My point about spatial information was not that it was very weak
but that it was only one of a number of cues for sound
separation.  To this should be added the idea that it may need
those other cues in order to be effective itself.

Al