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Article 6264 of comp.ai.philosophy:
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>From: erwin@trwacs.fp.trw.com (Harry Erwin)
Newsgroups: comp.ai.neural-nets,comp.ai.philosophy
Subject: Spectral Data Processing
Message-ID: <634@trwacs.fp.trw.com>
Date: 16 Jun 92 11:56:39 GMT
Followup-To: comp.ai.philosophy
Organization: TRW Systems Division, Fairfax VA
Lines: 28

I want to thank everyone who responded to my question. It turns out that
the aural processing system does use both phase and power (and _not_
zero-crossing (!?)) information to localize objects in sound space. Barn
owls use phase for left/right localization and relative power for up/down
localization, for example (Spence, et al., 1989, Neuronal maps for
sensory-motor control in the barn owl, NIPS 1).

I've seen three arguments against sonar holography. The first one is that
real-world objects typically move fast enough that they will blur during
the generation of a sonar hologram given the processing rate of the brain.
The second is that with only two points at which sound data are taken,
there is only enough dimensionality in the data to support a
two-dimensional scene. To gain a third dimension, a third, spatially
separated, data source is needed. The third argument is that the local
structure of the brain is insufficiently regular.  Any comments?

Also, two more questions:
1. Has anyone studied the lateral line organs of fish? The remarkable
coordination seen in schools of fish hints that communication via pressure
waves is responsible. 
2. Given the limited spectral response of retinal cells and the much
smaller wavelength of visible light, I find it hard to believe that the
eye would be able to detect relative phase. Any evidence here?


-- 
Harry Erwin
Internet: erwin@trwacs.fp.trw.com


