CetaceanCog

CetaceanCog - CS 143 * Animal Cognition Lecture 6: CETACEAN...

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CS 143 * Animal Cognition Lecture 6: CETACEAN COGNITION NOTE: Presume the following based on Bottlenose Dolphin ( Tursiops truncatus ) unless otherwise specified Perceptual Integration - A bit more on Echolocation - Each click is a broadband (multi-frequency, including super-sonic) high amplitude burst of sound - Exits forehead in narrow beam , focused & steered by nasal apparatus and melon - Clicks are sent out in a “ train ”, with more closely-spaced click trains => higher detail resolution - Click intervals adjusted per transit time to/from target, usually wait for echo before next click - Lag time (can be .003 sec !) - To humans, as clicks more closely spaced, echolocation sounds higher & higher pitched - NOTE: Sound travels 4.5 times faster in water than in air, so underwater echolocation requires VERY high speed processing - The brain (presumably) records the nature and timing of each outgoing click and compares it to the nature and timing of its returning echo… - The predominant frequencies in the echo will be those whose wavelengths (or λ s) best match the size of the target (where the higher the frequency, the shorter the λ29 - Frequencies that resonate with the target, per its material , are amplified in the echo - The longer the latency between click and echo, the farther away the target - Both of above can include subtle differences from 3D aspects of one target - Amplitude of echo also a function of both distance (via attenuation) & absorption - e.g. Air sacs reflect nearly all incoming sound, bones tend to absorb much - Infant dolphins produce first click trains in first few weeks, but learning plays a major role! - i.e. Learn to refine outgoing beam, tune it to target & ambient noise factors,
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This note was uploaded on 09/15/2011 for the course COGS 143 taught by Professor Johnson during the Spring '08 term at UCSD.

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CetaceanCog - CS 143 * Animal Cognition Lecture 6: CETACEAN...

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