CHAPTER 4 

 The Language of Echoes 



From our brief, qualitative look at the remarkable navi- 

 gational feats of some animals, it seemed clear that sound 

 was a most important message carrier. This led us to a 

 detailed examination of sound itself, particularly how it 

 echoes or reflects, in order that we might experiment 

 more skillfully and intelligently in an attempt to learn 

 how echoes are actually used by animals— what are their 

 limits, what aids or hinders, what physical characteristics 

 are especially suited to echolocation, what are the special 

 characteristics of the sounds these animals make. We 

 may hope to discover some important bits of evidence, 

 perhaps obscure at the moment, which will aid blind peo- 

 ple in their travels, and even if this does not occur, we 

 will certainly know our environment better. Men have al- 

 ways learned from animals, and even in this age of elec- 

 tronics and atomic structure we still have much to learn. 

 Since the bats are so expert in the use of echoes, let us be- 

 gin by examining in more detail the sounds they broad- 

 cast to produce the echoes which guide their agile flight. 



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