INDEX 



561 



transmission, 192-193 

 variations, 211 

 wave theory, 178-182 

 "Extinction cross section" of bubbles, 

 465-466 



Fathometer records for acoustic wakes 

 submarines, 501-502 

 surface vessels, 497-501 

 thickness and structure, 486-488 

 two-way vertical transmission loss, 

 507-509 

 Fermat's theorem of reverberation in- 



teasity, 253, 269 

 Fluctuations in sound transmission 

 beam echoes, 436 

 echo intensity, 377 

 interference, 167-170 

 magnitude, 158-160 

 microstmcture, lens action, 170-171 

 off-beam echoes, 437 

 probability distributions, 160-164 

 reverberation, 324^327, 335, 339 

 roll and pitch effects, 167-168 

 sound pulses, 211 

 space patterns, 167 

 supersonic frequencies, 241 

 time patterns, 164-167 

 Fluid velocity of sound waves 



see Velocity of sound in water 

 Fluorescein for acoustic measurements 



of wake-laying vessel, 491 

 FM sonar, reverberation from wide- 

 band pings, 75, 332-333 

 Forced vibrations of bubbles, 461 

 Forces in a perfect fluid, sound wave 



equation, 10-11 

 Fort Lauderdale, Florida, targets 

 strength measurements, 366, 368 

 Forward reverberation of sound, 80 

 Fourier theory in sound propagation, 



23, 36, 206-211, 329 

 "Free vibrations" of bubbles, 461 

 Frequencj' of sound 

 attenuation, 138 

 bottom reverberation, 338 

 "characteristics, 23-24 

 deep-water reverberation, 284-288 

 echo ranging, 408-410, 523 

 narrow-band pings, 329-331 

 periodmeter, 330 

 shallow-water reverberation, 240, 



318-319 

 sonic, 238-239 

 supersonic, 238-239 

 surface reverberation, 337 

 target strengths, 433 

 volume reverberation, 336 

 wide-band pings, 332-333 



Fresnel zone theory of target strengths, 

 356-360 

 applications, 358 

 convex surface, 359 

 cyUnder, 360 

 method, 356-357 

 sphere, 358-359 



Gaussian distiibution of sound in- 

 tensity fluctuations, 161-162, 

 326 

 Geometry of acoustic wakes 



see Wake geometry in sound trans- 

 mission 

 Grazing angle variation in reverber- 

 ation of sound 

 bottom scattering coefficients, 314^ 



318 

 transducer horizontal, 299-301 

 Ground wave in sound transmission, 



230-232 

 "Group velocity" of a wave train, 227 



Harbor detection equipment for sub- 

 marine wakes, 443 



Harmonic waves in sound propagation, 

 17-18, 22-23 



Heterodyned reverberation of sound, 

 339 



"Hidden periodicities" of sound in- 

 tensity fluctuations, 166-167 



"Highlight" in Fresnel zone theory of 

 target strengths, 357, 358 



Horizontal transmission of sound 

 beam echoes, 317-318 

 bottom reverberation, 321-323, 339 

 deep-water reverberation, 337-338 

 transmission loss, 504-507 

 transmission run, 79 



Hiigoniot equation for shock fronts, 

 180, 184 



HuU reflections of underwater sound, 

 415 



Hull wake in sound transmission, 478 



Huyghen's principle for reflected sound 

 pressure, 356 



Hydrodynamic theory of bubble forma- 

 tion, 449 



Hydrographic conditions for sound 

 transmission anomalies, 119 



Hydrophone depth in sound transmis- 

 sion, 72-74, 148-150 



Image effect in sound transmission, 95- 

 97, 190 



Image interference in sound field in- 

 tensity, 32-33, 163, 301 



Index of refraction, wave front equa- 

 tions, 44 



"Instantaneous frequency" of rever- 

 beration, 329-330, 339 



Intensity of echoes 



see Echo intensity measurements 

 Intensity of sound, 6 



see also Fluctuations in sound trans- 

 mission 



contours, 62-63 



experiments, 114-117 



formulas, 51-53 



interference effects, 168-170 



Unear gradients, 57-58 



phase distribution, 37-38 



plane waves, 21 



rays, 65-66 



reverberation, 265-266, 334 



scattering, 532 



shadow zone, 65-68 



spherical waves, 21-22 



thermocUne, 112-114 



transmission anomaly, 53-54, 58-59 



velocity-depth variation, 54-57 



wake measurements, 488-490, 504 



wave equation, 22 

 Interference effects in sonic transmis- 

 sion 



echoes, 377 



intensity, 168-170 



target strength measurements, 410 

 Interferometer for sound velocity meas- 

 urements, 17 

 Inverse square law for underwater 



sound, 6-7, 237, 345-347 

 Isothermal water, sound transmission 



absorption, 97-104 



attenuation coefficient, 104-107 



bottom reverberation, 313 



deep-water transmission, 238-239 



echo ranging, 109-110 



image effect, 95-97 



layer effect at 24 kc, 112-114 



layer effect at 60 kc, 117 



ray theory, 61 



short range transmission, 108-109 



temperature-depth pattern, 93 



thermocUne depth, 114-117 



transmission loss, 107-108 



transmission runs, 110-111 

 Iso velocity layer effect, ray acoustics, 

 56-57 



Kennard's theory of propagation of 



cavitation fronts, 191 

 Khintchine's theorem, self-correlation 



coefficient for sound intensity 



fluctuations, 167 



Lambert's law for surface reverberation 

 of sound, 300, 314 



Laminar cavitation in bubble forma- 

 tion, 449 



