The blind man who taught himself to see

Re:The blind man who taught himself to see by jacobolus on Friday March 04, 2011 @03:34AM (#2287478)

The eye ends up taking in a lot of information from every point you look at though, whereas the ear is always listening in every direction at once. Because of the kind of processing in the eye and brain, our three types of cone cells actually end up capturing most of the information encoded in the different reflectance spectra of the kinds of objects that naturally occur in the world (most of the variation occurring in typical objects in the wavelength range we can detect): today with synthetic materials and various lighting sources metamerism is noticeable in special edge cases, but just wandering around it usually doesn’t matter too much. After all, a decent percentage of males get along just fine as dichromats, and many don’t even realize they’re missing anything until adulthood (because even with two sensor types there is a lot of variation to pick up).

I think it’s pretty silly to argue that hearing can pick up more detailed information about the world than vision can: from vision, we can figure out shape, orientation, distance, texture, gloss, material, lighting, direction and speed of extremely tiny motion, etc., and we can do it for fine details of everything we look at, thereby constructing a tremendously detailed model of our environment without needing to directly touch every part of every thing. Anyway, both hearing and vision are extremely sophisticated. The two gather quite dramatically different kinds of information. Neither should be underestimated.

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Re:The blind man who taught himself to see by Derbasti on Friday March 04, 2011 @03:56AM (#2287512)

Of course, this is completely true. But note that I did not talk about the amount of information but the precision of information. Also note that every cone cell is equivalent to one hearing cell in the cochlea, of which there are plenty, too. (Only in the eye, they are distributed spatially while in the cochlea, they are distributed by frequency)

But all this is really not as important as the signal processing that makes sense of it. There are interesting connections between hearing and seeing. If you watch TV and someone at your side turns his head to you in order to speak, you will notice and shift your attention to him. You will think that you saw his head movement in the corner of your eye. But truth is, many people wearing hearing aids will not notice the same situation, for the simple reason that you actually did not see his head movement, you heard it.

There are many more examples where things like this happen. What you perceive is different from what your senses detect. All these intricate combinations of sensual information are the really interesting part.

Another fun thing about hearing: The human ear can detect very low sound pressure levels. Actually, it will detect a displacement of the eardrum of about the diameter of an air molecule. In a way, this is saying that the ear can detect the impact of individual air molecules on the ear drum (not really true, but in the ballpark). That is freaking amazing.

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