Re: HC selectivity ... was Re: Physiological models of cochlea activity - alternatives to the travelling wave

[Matt Flax <flatmax@xxxxxxxx>]

Yes - thanks for correcting me Bob.

Allow R to vary from 15 to 80 Meg Ohms ... as per the reference.

R= 15 Meg Ohms  ...  taken from [4] for example
C= 1 pF         ...  taken from [5] for example

This is about 10 kHz ... more accurate measurements will most likely 
take this figure to higher frequencies.

Whilst this seems low - as we can hear up to 20 kHz, my initial 
statement on hair cell selectivity is this :
The resistor capacitor model of the basolateral hair cell membrane is 
flawed. It is flawed for these reasons - as well as others :
a] Membranes are not linear and can't be modelled by a resistor and 
   capacitor.
b] Cells have active elements ...

I predict that the affect of any 'selectivity' will be around 5% of the 
total signal level through the hair cell - maximum. This is due to the 
hair cell activity.

Hair cells are excellent instantaneous transducers. My upcoming thesis 
will prove this... using a physiological model.

Matt

On Fri, Sep 28, 2007 at 08:24:35AM -0400, Bob Masta wrote:
> On 28 Sep 2007 at 12:55, Matt Flax wrote:
> 
> <snip>
> 
> > With respect to a hair cell at rest ... take the following general 
> > values for membrane resistance and capacitance :
> > R= 40 Meg Ohms  ...  taken from [4] for example
> > C= 1 pF         ...  taken from [5] for example
> > The first order cut-off frequency would be about 25 kHz.
> > fc=25 kHz.
> 
> How do you obtain this 25 kHz value?  Using
>    f = 1 / (2 * pi * R * C)
> I come up with about 4 kHz.
> 
> Best regards,
> 
> 
> 
> Bob Masta
>  
>             D A Q A R T A
> Data AcQuisition And Real-Time Analysis
>            www.daqarta.com
> Scope, Spectrum, Spectrogram, Signal Generator
>     Science with your sound card!

-- 
http://www.flatmaxstudios.com/
http://www.flatmax.org

Public Projects :
http://sourceforge.net/search/?type_of_search=soft&words=mffm
http://www.psysound.org