564 



INDEX 



Ship draft and tonnage, effect on target 



strengths, 432 

 Shock wave fronts, sound transmission, 

 174-186 

 law of similarity, 182 

 Rankine-Hugoniot theory, 177, 179- 



181 

 Riemanii's theory of waves of finite 



amphtude, 176-179 

 structure and decay, 184-186 

 thickness of pressure region, 182-184 

 Short-range sound propagation, 108- 

 109, 193-211 

 diffraction hypothesis, 201-206 

 Fourier analysis, 206-21 1 

 pulse measurements, 193-197 

 refraction effects, 197-200 

 shadow zones, 200-201 

 transmission variations, 108-109, 

 211 

 Similarity law for shock waves, 182 

 Sinusoidal sound experiments, 192 

 Shde rule for sound ray tracing, 59 

 "Slipstreams" in sound transmission, 



478 

 Snell's law of refraction for bottom re- 

 verberation of sound, 318 

 Sonic transmission 



analysis of records, 83-84 

 deep-water, 238-239 

 frequency effects, 138-139 

 listening gear, 87 

 Long Island area survey, 155-156 

 Pacific Ocean measurement.*, 156 

 shallow-water, 240 

 summary, 156-157 

 "Sound channel" propagation 

 deep sound channels, 213-216, 240 

 experiments, 216-219 

 long range transmission, 211-213 

 surface sound channels, 239-240 

 temperature gradients, 133-135 

 Sound field measurements 



see Transmission loss measurements 

 Sound propagation in liquid containing 

 many bubbles, 467-477 

 acoustical observations, 474-477 

 reflection, 473-474 

 scattering, 470-473 

 theory, 467-469 

 transmLssion, 469-470 

 Sound range recorders for wake meas- 

 urements, 484 

 Sound transmission, underwater 



see Fluctuations in sound transmis- 

 sion; Transmission of sound, 

 deep-water; Transmission of 

 sound, shallow-water 

 Sources of sound 



see also Explosions, underwatei 

 directivity, 24-27 



echoes, 420-421 

 frequency, 23-24 

 levels, 347-348, 434 

 transmission runs, 72-74 

 Space pattern of fluctuation of sound 



intensities, 167 

 Spectrum level in Fourier analysis of 



explosive sound, 208-209 

 Sijecular reflection of sound 

 beam echoes, 415-417 

 convex surface, 434 

 frequency factors, 410 

 Fresnel zones, 356 

 surface vessel, 430 

 target strengths, 373-374 

 Speed of ship, effects on target 



strengths, 402, 431 

 Sphere target strengths 

 definition, 434 

 derivation, 348-350 

 Fresnel zone theory, 358-359 

 Spherical sound waves, 21-22, 41-42 

 intensity, 21-22 



pressure versus fluid velocity, 20 

 ray acoustics, 41^2 

 wave equation, 18-19 

 "Spines" of echoes in surface-reflected 



sound, 373-374 

 Split-beam patterns in ray acoustics, 



61-62 

 Standard reverberation level of sound, 



259 

 Stationary waves in underwater sound 



see Normal mode theory of sound 

 Still vessels, target strengths, 424—425, 



437 

 Stoke's hypothesis for attenuation of 



sound, 28 

 Submarine reflectivity, 379-381, 386 

 Submarine tactics in sound transmis- 

 sion, 4 

 Submarine target strengths, 388-421 

 altitude angle, 393-397 

 aspect angle, 388-393 

 asymmetry, 400-402 

 beam echoes, 413-417 

 frequency, 408-410 

 measurements, 397-400 

 oceanography, 410-413 

 off-beam echoes, 417-420 

 orientation, 388 

 puLse length, 404-408 

 range, 402-404 

 source, 420-421 

 speed, 402 

 Submarine wakes, acoustic measure- 

 ments 

 echoes, 523-526 

 experiments, 501-502, 538-539 

 Supersonic transmission 

 data-analysis, 80-84 



deep-water, 238-239 



frequency effects, 138 



listening gear, 87 



sea bottoms, 139-141 



summary, 153 



transmission runs, 141-153 



velocity gradients, 142-150 



wind force, 152 

 Surface reverberation of sound 



average levels, 304-306 



definition, 259 



elimination, 281 



grazing angle, 300-302 



index, 262 



intensity, 259-263 



"level" concept, 263-264 



multiple scattering, 303-304 



ping length, 302 



range, 289-299 



reflection effects, 270-271 



scattering coefficient, 306-307, 337 



summary, 336-338 



wind speed, 298-299 

 Surface vessel target strengths 



aspect angle, 424-428 



deep-water transmission, 527-530 



frequency, 433 



introduction, 422 



measurements, 422-424 



pulse length, 432 



range, 426-431 



reflection, 437 



ship type, 432 



speed, 431 



wake echoes, 497-501 

 Surface-reflected sound 



fluctuations, 377 



i-everberation, 301 



short-range propagation, 196 



summary, 243 



transmission loss, 373-374 



Target strength measurement 

 approximations, 352-353 

 calibration errors, 368-369 

 comparison of methods, 387 

 computation, 358-360 

 convex surface, 434 

 cylinder, 435 

 definition, 347-348 

 echo variability, 374-378 

 experiments, 363-366 

 Fresnel zones, 356-358 

 introduction, 343 



Massachusetts Institute of Tech- 

 nology, 379-381 

 mathematical theory, 353-355 

 Mountain Lakes, N. J., 381 

 nonspecular reflection, 361 

 principles, 363-364 

 pulse length, 350-351, 362 



