CONCLUSIONS 



I. THE UNDERWATER SPARK SOUND SOURCE 



1. An underwater spark is capable of providing very high 

 intensity, broadband, nondirectional short pulses of acoustic 

 energy. 



2. Resonators excited by an underwater spark are capable 

 of providing selected frequencies or bands of frequencies 

 of acoustic energy. 



3. The apparatus required for a high-powered underwater 

 spark is suitable for assembly in a capsule for deep submer- 

 gence. 



4. An underwater spark is useful in explosive metal forming. 



II. THE PNEUMATIC SOUND SOURCE 



1. Small rubber spheres are capable of providing acoustic 

 source levels of at least 107 db above 1 dyne/ cm^ at selected 

 frequencies within the band 10 - 300 c/s. 



2. The frequency of a given pneumatic source can be con- 

 trolled by selection of its depth at the time of rupture. 



3. The nature of the simple pneumatic source makes it 

 appear useful in a variety of applications requiring a single 

 pulse of selected frequency within its operating band. 



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