Re: Streams

[Bruno Repp <repp@xxxxxxxxxxxxxxxxxxxxxx>]

Dear List,

I was correct in my prediction that Al Bregman would provide cogent
comments after my rash reply to an earlier message to this list.
Still, it seems to me that the concept of a single stream, as
discussed by Al, does not have much utility or explanatory value. It
does so only when it is contrasted with at least the possibility of
multiple streams. In other words, a single stream is a default
condition of little theoretical interest. This is equally true for a
single group. Groups become interesting only when there are (or could
have been) two or more of them.

Then there is the question of whether much is to be gained by talking
about two streams occurring in succession. This amounts to saying
that two successive acoustic events are perceived as coming from
different sources or locations. There is nothing wrong with calling
these events different streams, but neither does it add anything
significant to saying that the perceived source or location has
changed. Moreover, the term stream seems increasingly less
appropriate as the temporal interval separating successive sound
events increases. I doubt that events separated by 1 day, 1 hour, or
even 1 minute should be considered as belonging to the same stream,
even if they are perceived as coming from the same source. It seems
to me that a stream, to be properly so called, should be temporally
coherent, which may mean that not more than a few seconds should
intervene between its elements. Consequently, the idea of hearing two
different streams may become pertinent only when the streams are
separated by less than a few seconds.

Without any doubt, however, most or all research on stream
segregation has been conducted with temporally overlapping series of
(usually rapidly paced) sounds. This is why I thought that temporal
overlap (including perhaps very brief separation) is an essential
part of the definition of streams. Al's definition clearly is
broader, but this is more of a terminological issue. Streams really
come into their own only when they occur at more or less the same
time.

With regard to the role of attention in stream formation, this is an
interesting empirical issue that certainly needs more research.

--Bruno

Bruno H. Repp
Research Scientist
Haskins Laboratories
270 Crown Street
New Haven, CT 06511-6695
Tel. (203) 865-6163, ext. 236
FAX (203) 865-8963
e-mail: repp@haskins.yale.edu