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

```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!

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```

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