244 



SUMMARY 



simultaneous recordings at a number of different 

 frequencies. Increasing complexity of the necessary 

 equipment may probably be anticipated. 



It is possible that explosive sound may be useful 

 as a research tool. As pointed out in Chapter 9, short 

 explosive pulses provide resolution of the direct and 

 reflected pulses even at nearly grazing angles and 

 also reveal clearly any multiple ray paths that may 

 be present. By means of Fourier analysis, it is possible 

 also to obtain with explosive sound many of the re- 

 sults which could be obtained by simultaneous trans- 

 mission of many single frequencies over the entire 

 spectrum. Finally, the high sound intensities possible 

 with explosive pulses can provide data at longer 

 ranges than are possible with standard sound pro- 

 jectors. Thus, explosive sound would appear to be a 



valuable tool of underwater sound research, deserving 

 wider application than it has had in the past. 



Regardless of what specific technique is used, the 

 primary requirement for any basic experiment is that 

 it be devised to give answers to certain physical 

 questions rather than to operational problems. To 

 satisfy this requirement, the theory underlying each 

 experiment must be studied in detail before the ex- 

 periment is actually performed to make sure that 

 the results obtained will be significant. Considerable 

 ingenuity may be required to find means for isolating 

 the eflects of the different factors involved in order 

 to investigate them separately. It is only by such 

 carefully designed experiments that our general un- 

 derstanding of sound in the sea can be continually 

 increased. 



