48 



THE NAVY OCEAN SCIENCE PROGRAM 



TURSIOPS TrUNCATUS — BOTTLENOSED PORPOISE 



0.2 0.4 



TIME-SECONDS 



0.6 



Sonogram of the bottlenosed porpoise, illustrating the change in frequency 

 of the porpoise squeal as a function of time 



The natural sounds include breaking waves, wind, rain, 

 earthquakes (seismic noise), and the sounds of marine animals. 

 While some of these are usably predictable if the weather is 

 known, only limited knowledge is available for either earth- 

 quakes or biological sounds. As previously discussed, a significant 

 effort has been placed on the identification of sounds of biological 

 origin. A very large field of investigation remains on these 

 sounds. Seismic noise, a significant concern to naval sonar 

 designers, has received limited attention in this program. 



The sounds generated by man are mostly industrial noises 

 transmitted into nearby coastal waters and sounds made by 

 ships and submarines. Since many of the detection-system 



