Subject: Re: Directional Perception From: Tom Brennan <g_brennantg(at)TITAN.SFASU.EDU> Date: Wed, 17 Jan 2001 10:04:34 -0600Hi John. Actually, this is a certain group of psychologist's definition of echo location. The blind, those in the blindness field, and many in perceptual psychology use echo location as a term to identify sound whether produced by the individual or in the environment. For example, when I walk down a street, I can "hear" sigh posts and trees but it is through no sound that I make. I use self produced sounds for echo locating over distances generally of 20 feet or more. When I walk and hear environmental items such as signs, I am largely using the echos produced by environmental sounds echoing from those objects. The low frequency component is primarily what is used for basic detection (around 500Hz, but the high frequency (above 8000Hz and likely more above 11000Hz is what gives definition (clearness) to objects. Tom Tom Brennan, CCC-A/SLP, RHD web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html web master http://titan.sfasu.edu/~f_freemanfj/speechscience.html web master http://titan.sfasu.edu/~f_freemanfj/fluency.html