Re: Cochlea Amplifier models : a new list

[Martin Braun <nombraun@xxxxxxxxx>]

Erik Larsen wrote:

> The data in that figure (nerve response as a function of stimulus level, 
> Fig. 7B) can be taken to suggest any number of things.

This is an unscientific way of talking.


> Your interpretation is one possibility, but I could give you several 
> others. For example, as sound level goes up, the fiber's response area 
> broadens, especially towards lower frequencies.

This is not relevant, because rate level peaks are clearly discernible.


> This would be entirely consistent with the BM tuning dependence on level, 
> combined with a saturating response of the fiber. The fact that at 100 dB 
> only (not 90 dB) there appear to be two best frequencies could be 
> attributed entirely to the stochastic nature of the fiber response, i.e. 
> at 5.5 kHz the response just happens to be a bit low (only 10% below 
> maximum). There are no error bars so it is not clear whether this is a 
> real dip in the response or not. My interpretation isn't any better or 
> worse than yours if neither of us can offer a stochastic model of the 
> fiber response that explains this data. Its all to easy to find features 
> you are looking for, otherwise.

A "stochastic model of the fiber response" is not needed. The rate count 
figures are so high that their significance need not be tested by further 
mathematics.

> Another problem is that this data is from the 6 kHz CF place - I assume 
> this is not in the basal turn for squirrel monkey so we really do not know 
> the BM mechanics at that point.

The 6 kHz CF place of the squirrel monkey corresponds to the 3 kHz CF place 
in humans. Also these things are in the literature!

Martin



----- Original Message ----- 
From: "Erik Larsen" <elarsen@xxxxxxx>
To: <AUDITORY@xxxxxxxxxxxxxxx>
Sent: Thursday, October 11, 2007 5:01 PM
Subject: Re: Cochlea Amplifier models : a new list