Re: comparing cochlear models ?

[Bastian Epp <Bastian.Epp@xxxxxxxxxxxxxxxx>]

Dear list!

As the comparison and evaluation of cochlear models is exactly what 
bothered my during the last year (or so), I think I want to share my points:

In general, it is very interesting to compare and to evaluate models of 
the cochlea...even though that is sometimes quite hard due to different 
approaches.

I agree with the view, that one way to evaluate cochlear models is to 
look at their performance to account for many different datasets 
(physical (OAE), physiological(I/O) and even psychoacoustical) 
simultaneously with a "decent" amount of fixed parameters....but 
especially for the psychoacoustic paradigms, the potential for arguing 
starts at the metric which is evaluated to account for the data. So 
maybe one should start with physiological data and/or use very simple 
(and still feasable) approaches for psychoacoustics. Some ideas as a 
starter:

Excitation patterns:
Evaluation of the shape of the excitation pattern (slopes basal/apical, 
Q-factor, ...) in a panoramic view (whole cochlea) and at a single place 
for different frequencies (place-fixed view).

I/O-functions:
Evaluation of the response of the model at a fixed place for different 
levels of the same frequency

OAE:
Propagation of the cochlear activity through a simple model of the 
middle ear (which should be comparable as long as the used middle ear is 
linear).
Phase-issues with evoked (e.g. CEOAE) emissions?

Two-tone suppression:
Here it's getting neccessary to define the metric which is evaluated, 
but there should be the phenomenon of a nonlinear interaction of two 
tones...independently of the analysis which is applied.

...

All these measures should be relatively robust against absolute scaling 
and hence be comparable and (if the model is supposed to be "realistic" 
in one sense or the other) in line with data.

I see a big chance in that, since different models account (and are 
developped for) different aspects of cochlear functioning, and all 
reflect a special case of THE cochlea which was implemented by nature.

We did the things mentioned above (and some more) using the 
Duifhuis-Transmission line in a modifed form. I would be happy to share 
ideas with anybody who is also interested. We are also preparing a 
manuscript and I am also happy to share that as soon as it is in a 
readable form. (BTW: Thx Jon for sharing the manuscript, nice collection 
of data and a good start for discussions....)

If anybody read the message until here: Sorry for the length.

Best from Oldenburg

BAstian