46 THE NAVY OCEAN SCIENCE PROGRAM 



E-lt; 





100 



I 200 



300 



400 



u<:^FySE SMTTERING 



:;!ll*si-t_.^^-'? 



r-ri 5 * * ,-^ ^ Cj ^ (Ss-. 



LOWS? - - ' \ 



SCATiaWG ^' ■ ' h 



ikm 



PHYSONECTS 

 to TO 60 CM. 



DEEP SCAHERING LAYER • myctophids 



8 TO 10 CM. 



J L 



1600 1830 1700 1730 1800 1830 1900 1930 



TIME 



The deep scattering layers scatter sound as from bubbles of gas which resonate 

 at certain frequencies according to their size and depth. Both small fishes Mycto- 

 phids and Physonects have such gas bubbles for adjusting their buoyancy. The 

 observations made from a diving saucer by Navy Electronics Laboratory scien- 

 tists show the relationship of these animals to the scattering layer off the coast 

 of California. 



to arrive by theory and measurement at its effect on acoustic 

 applications in a much more quantitative sense than is presently 

 available. 



The effects of the variability of the ocean (in each of the 

 above areas) on classes of acoustic transmitting and receiving 

 systems are subjects of study. This subject is discussed further 

 in this report in the section titled "Prospects for the Future." 



Noise in the Oceans 



The oceans contain many natural sound makers and many 

 noisemakers powered by man. These sources of sound must be 

 identified in order to understand and predict their effect on 

 communication and detection systems. 



