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How the cochlea computes (2024)

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475 points izhak | 1 comments | 30 Oct 25 17:01 UTC | HN request time: 0s | source
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adornKey ◴[30 Oct 25 18:14 UTC] No.45763186[source]▶
This subject has bothered me for a long time. My question to guys into acoustics was always: If the cochlea performs some kind of Fourier transform, what are the chances, that it uses sinus waves as a base for the vector-space? - if it did anything like that it could just as good use any slightly different wave-forms as a base for transformation. Stiffness and non-linearity will for sure take care that any ideal rubber model in physics will in reality be different from the perfect sinus.
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1. kragen ◴[31 Oct 25 06:01 UTC] No.45768849[source]▶
Oh, it turns out that complex exponentials are the eigenfunctions of linear time-invariant systems, and sound transmission is full of linear time-invariant systems. So surely ears cannot be perfectly detecting sinusoids, but there's a lot of evolutionary pressure to come as close as possible. That way, you can still recognize a birdsong or the howl of a wolf even if it echoes off a cliff, or recognize your baby crying even if it is facing the other way.