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Cochlear Models

Our group at Apple has released a couple of cochlear models that other auditory
researchers might find useful.  These services are free.... we find these
tools useful for our own work, but we can't support them as you would expect
normal products.   If you find them useful as they are, great!

We use two different models in our daily work.
        1)      The Patterson-Holdsworth Auditory Filter Bank - Based on a
                critical band auditory model.  This is a linear model with
                fairly modest computational requirements.

                A Mathematica technical report is now available that describes
                a new more efficient implementation.  This technical report
                includes C, Fortran, and Matlab code to design the filters.
                Matlab code to implement the filters is also shown (it
                is only three lines long.)

                To get this report use anonymous FTP to ftp.apple.com.  Look
                for the Gammatone.* files in the /pub/malcolm directory.

                Or send me a note with your postal address and we can send
                you the notebook (includes a paper copy and a Macintosh disk
                with the electronic copy ready for you to modify.)

        2)      The Lyon Passive Shortwave model - Is a nonlinear model of
                cochlear behaviour based on a passive non-linearity and a
                shortwave model of cochlear hydrodynamics.  We're working on
                a better model, but this is all we have to offer for now.

                Both a technical report and running code were released a couple
                of years ago.  The code still works and runs on just about
                any Unix machine or a Macintosh.  Other people have ported
                it to DOS.

Finally, we're also offering cochlear modeling by mail.  We've established
a service where you can send an audio file to a special email address, we
compute the cochleagram or correlogram on our Cray, and send you back the
picture or the movie by return email.  The interfaces are a bit shakey yet,
but we're working to make it more stable.  (I used the service to settle an
argument while I was at ARO in Florida a few months ago.)  Both the Lyon
and the Patterson cochlear models are available.  Let me know if you would
find this useful or would like to give it a try.

Send me email if you want the Gammatone Tech Report, have any questions, or
want more information.

                                                Malcolm Slaney
                                                Apple ATG Perception Group