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Re: Blind Source Separation by Sparse Decomposition
- To: AUDITORY@xxxxxxxxxxxxxxx
- Subject: Re: Blind Source Separation by Sparse Decomposition
- From: "Richard J. Fabbri" <fabbri@xxxxxxxxxxx>
- Date: Wed, 8 Sep 1999 18:33:45 -0400
- Comments: To: Al Bregman <email@example.com>
- In-reply-to: <Pine.SUN.3.95.990908122648.13940Dfirstname.lastname@example.org .ca>
- References: <email@example.com>
- Reply-to: "Richard J. Fabbri" <fabbri@xxxxxxxxxxx>
- Sender: AUDITORY Research in Auditory Perception <AUDITORY@xxxxxxxxxxxxxxx>
If you have ever heard (voltage comparator per my email) clipped
speech (nth approximation to Licklider's "infinitely-clipped" speech)
then, you know the remarkable job our hearing does perceiving the
spoken word via zero-crossings. Yes, assumptions such as band
limiting and zero-mean reduce the universe of possible signal
reconstructions once given a measured set of zero-crossings.
But, these ideas can also be appreciated as schema satisfying
Time-Domain boundary conditions where the "boundaries" are
My reason for proposing Binaural audition w/ clipping is probably
becoming quite clear but, I will not write that reason hear. Anyone
who wants to witness a startling demo of "stream segregation",
otherwise known to Cherry as "The Cocktail Party Effect", should
simply playback a Binaural recording thru voltage comparators
and listen to those comparators through stereo headphones.
While listening to these reconstructed (Binaural) spatial sources,
recognize that we're not discussing theory ... we are:
- Demonstrating psychoacoustics
- Demonstrating source "segregation" via zero-crossings.
Primarily period & interaural delay are encoded by zero-crossings.
Most of the additional (directional) encoding, caused by pinnae and
head diffraction, have been removed from the Binaural signals found
at the L/R comparator outputs, i.e., some degradation of Front/Back
and Up/Down discrimination will be experienced while listening to
clipped Binaural recordings.
But, can anyone explain these reconstructed spatial sources via a
frequency analysis of "infinitely-clipped" (Binaural) channels?
If not, then, how SHOULD we approach the CASA problem?
Are there other tools and models we have ignored?
Finally, there are better approaches to zero-crossing reconstruction,
i.e., perceived with high fidelity but, these require a time-domain
theory that will make no general progress thru our community
while frequency analysis remains unquestioned.
Try the above experiment.
How do zero-crossings help us separate spatial sources?
Can you explain this zero-crossing effect using frequency analysis?