INDEX 



Acoustic energy, 46; in water, 

 19 



Acoustic orientation, 32. 

 See also Echolocation 

 and Orientation 



Acoustic probing, 116-20 



Acoustics: architectural, 50; 

 echoes, 57-73 



Aerial interception, 18 



Air, 19, 40, 44, 97, 116; 

 molecules of, 39; sound in, 

 25 



Airplanes, 17, 120 



Amazon River, 21 



Amplitude, 36 



Angle of incidence, 77 



Angle of reflection, 77 



Animal Navigation, 148 



Animals: domestic, 148; 

 echoes, use of, 10; lu- 

 minescent, 19; nocturnal 

 vision of, 27, 32; orientation 

 in darkness, 27-28; see also 

 Bats 



Antennae, 54 



Apparatus. See Equipment 



Aquaria, 26 



Architectural acoustics, 50 



Auditory nerve, 20 



Barnes, H., 147 



Bats, 2, 18, 26-32, 44, 121-22, 

 127, 148; acoustic orienta- 

 tion, 32; brown bats, 85, 

 88, 93; chirping bats, 87; 

 chirps, 87; ears, 28; echo- 

 location, 29, 78, 90-95, 99- 

 100, 112; fish-catching, 

 95-99; flight, 89-90; FM 

 bats, 87, 95, 97, 113, 116, 

 125; foods, 28, amount of, 

 88-89; horseshoe bats, 

 84-85, 87, 116; impair- 



ments: of mouth, 29, of 

 sense organs, 28-29; jam- 

 ming, 103; nature of, 26-27, 

 31; navigation, 2, 27, 32, 

 108; objects, small, 104; 

 obstacles, 31, 93-95, 100-1, 

 discriminating ability, 103- 

 4; orientation, 32, 51-53; 

 orientation sounds, 29-31, 

 84-87; rhythm, 89-90; 

 sonar, 148; sound intensity, 

 97-98; sounds: frequencies, 

 2, 29-30, 84-87; vampire 

 bats, 85; whispering bats, 

 85, 87, 95 



Beat frequency, 111-12 



Beat note, 111-12 



Bell Telephone Laboratories, 

 148 



Biology, 10 



Biophysics, 26-27, 56; defini- 

 tion, 132 



Birds, 148 



"Bird Sonar," 148 



Blindness, 10, 17, 20, 129-44; 

 facial vision, 131, 135; 

 orientation, 130; sound pro- 

 ducers, 143-44. See also 

 Vision 



Blindness, 150 



Blind people, 18, 26, 148, 

 150; activities, 131; echoes, 

 24, use of, 67; echolocation, 

 73, 110, 112, 143; orienta- 

 tion, 44; orientation prob- 

 lems, 100; orientation 

 sounds, 107; sound dis- 

 crimination, 104-5; sound 

 fields, 51 



Bowen, E. G., 147 



Boys, C. v., 147 



Brains, 10, 20, 56, 64 



Brown bats, 85, 88; obstacles, 

 93. See also Bats 



151 



