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

[Reggie Weece <weece@xxxxxxxx>]

Bob and Matt -

The difference between your two values for the cut off frequency
appears to be the 2pi factor.  From
http://en.wikipedia.org/wiki/RC_circuit,
wc = 1/(RC)  rad/s
fc = 1/(2piRC)  Hz

Thus wc = 25000 rad/s (not 25 kHz, as Matt suggested!)
Bob's calculation of fc = ~4kHz is correct.

- Reggie

> Date:    Fri, 28 Sep 2007 08:24:35 -0400
> From:    Bob Masta <audio@xxxxxxxxxxx>
> Subject: Re: HC selectivity ... was Re: Physiological models of cochlea activity - alternatives to the travelling wave
>
> 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