Re: streams and groups

[Peter Lennox <peter@xxxxxxxxxxxxxxxxxxxxxxxx>]

I'd just observe that it is quite interesting that we use a collective
description for 'many claps': "applause", and the same goes for rain; we
don't say "listen to the raindrops" when there are too many to possibly
count (or even individuate). In both cases, the difference between single,
or small numbers of, events and the large numbers which are perceived as a
'stuff' or 'process' (I'm not sure which, though favour 'stuff') seems
qualitative rather than quantitative. This does seem to be something to do
with the homogenising of transients, and I would guess that one could view
this as a sort of overload of the pinnae's capabilities to disambiguate
according to direction. I also suspect that frequency (audio, I mean, not
frequency of clapping!) is quite important, as both rain and applause can
behave quite like 'hiss' or white noise, if you try gentle head-turning.
There's a sort of 'phasy' effect.
>From an evolutionary point of view, one could perhaps understand why the
percpetual individuation of raindrops might be somewhat less than urgent.
apologies for butting in!
regards,
ppl
---- Original Message -----
From: "Bruno Repp" <repp@ALVIN.HASKINS.YALE.EDU>
To: <AUDITORY@LISTS.MCGILL.CA>
Sent: 14 May 2001 22:38
Subject: Re: streams and groups


> I apologize for replying to John Bates before Al Bregman does;
> undoubtedly, his reply will be more cogent than mine. But here is my
> answer to John's questions:
>
> >   As I understand the discussion here, each clap in a clapper's stream
of
> >claps could be considered to be a group.
>
> In Al's terminology, each clap is a unit. I would call it an event.
> It is a group only in the trivial sense that units and events are
> groups consisting of a single element.
>
> >Or is it that each clapper's
> >stream of claps is a group?
>
> Yes, a stream can be considered a group of a special kind--one that
> is temporally interleaved with other groups and consists of a
> substantial number of similar units.
>
> >In any case, further parsing of my applause
> >would reveal that every individual clap is itself composed of streams
> >and/or groups of smaller identifiable transient events.
>
> That seems unlikely to me: Each clap is just a single transient.
> However, there are more complex auditory events that can indeed be
> decomposed into smaller elements that are perceptually grouped
> together.
>
> >   But when you, Al, finish a presentation, the audience explodes with an
> >ovation that is a flow of hundreds of homogenized hand-clap sources.  You
> >can no longer pick out the streams and groups.  The applause you get is a
> >single amorphous spatially distributed stream of noise.  What happened to
> >the groups?  And is it important to know this?
>
> I have never been in this situation (there is usually total silence
> after I finish a talk), but I would say the mixture of sources
> contains a large number of potential streams that the listener's
> perceptual system is unable to segregate. The sources and streams are
> physically there but difficult to detect. By placing a  microphone a
> few inches from the hands of any individual clapper, the stream of
> his/her claps can be isolated and made perceptible.
>
> --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
>
>