THE PROBLEM 



Design and develop novel low-frequency sound sources. 



RESULTS 



Two different types of high-intensity sound sources have 

 been developed which have both military and commercial 

 potentialities: 



1. The underwater spark sound source is suitable for 

 explosive echo ranging, particularly from a submarine, 

 and shows promise as a source for long-range, active 

 detection and for long-range underwater signaling. The 

 underwater spark is safer than chemical explosives and, 

 unlike them, is repetitive. It is simple, reliable, and easily 

 adapted to working at great depths. Its short -duration pulse 

 allows discrimination against reverberation and is too short 

 to "home on, " particularly if single -pinging or staggered 

 repetition rates are used. 



This source has been tested at a depth of 300 feet 

 below the surface and generated peak pressures corresponding 

 to an acoustic level in excess of 3 million watts for a broad- 

 band nondirectional condition. In the 1000-4000-c/s frequency 

 band, a corresponding acoustic level in excess of 300, 000 

 watts was developed for a nondirectional condition. 



2. The pneumatic sound source , operating models of 

 which were built and tested extensively, is probably the 

 simplest generator of underwater sound yet discovered (in 

 its lightest form it weighs less than 1 pound). This source 

 has generated a peak acoustic level of over 4000 watts for 

 a nondirectional condition, in the frequency range between 

 5 and 300 c/s. 



The pneumatic sound source is suitable for ASW 

 operation; conversion of coastal defense passive systems 

 into active systems; explosive echo ranging; mine counter- 

 measures; anti-limpeteer operations; and coded signaling. 

 Typical commercial applications could be geophysical 

 prospecting and explosive metal forming. 



NIBL/WHOI 



D3Q1 DQ^DSS^ 



