Subject: Re: HC selectivity ... was Re: Physiological models of cochlea activity - alternatives to the travelling wave From: Matt Flax <flatmax@xxxxxxxx> Date: Sat, 29 Sep 2007 16:21:31 +1000 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>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