[carlob]

I once went to a 3h long blackboard talk given by James Hudspeth [1] on the physics of hearing.

It was one of the most fascinating things I've ever heard: it turns out that not only the cochlea performs a Fourier transform of the sounds we're hearing, but it can also selectively amplify some frequencies, by vibrating the very same hair that detect the sounds.

Sometimes the mechanism that amplifies some sounds goes wrong and that's why sometimes old dogs seem to emit a high pitched sound from their ears, and also the cause of some forms of tinnitus.

If you have some time to kill do go read the wikipedia pages of the cochlea and hair cells, it's really fascinating stuff!

[1] http://www.rockefeller.edu/research/faculty/labheads/JamesHu...

[HCIdivision17]

I have always wondered if that high pitched sound was real! No one else heard it, and it makes so little sense I always figured it was my hearing.

[72deluxe]

Do you hear that high-pitched sound all the time? That's tinnitus.

Or do you only hear it from dogs?

[HCIdivision17]

It turns out I have really decent hearing. So it's unlikely to be tinnitus; at worst I have a sort of hearing after-image when a tonal frequency suddenly cuts out (and now I'm guessing that's an effect of the ear actively filtering - I can't wait to watch that video).

But yeah, I did hear it on the dog. It's so anomalous to hear a high pitched noise coming from an ear that I was willing to question my own hearing/sanity. The best I could manage to guess was that there was some sort of small gas pocket leaking, which made a little bit of sense since my dog (samoyed) had a bubble on his ear (that eventually gave him a sadly adorable floppy ear when it eventually drained - prolly an aural hematoma); the bump never actually seemed to deflate due to the noise, though. At the time I was an early teen just sort of beginning to learn analytical techniques, so that reasoning was the best I could muster. These days I tend to trust/understand my senses more.