OBJECTIVE 
Since there are no inexpensive acoustic sources in the 5 to 50 Hz spectral region for 
generating controlled underwater sounds, investigate a newly designed nonresonant source 
of the mechanical type. Build and demonstrate operation of the new type projector at a 
source level of about 172 dB re | Pa at | m. ; 
RESULTS 
1. The nonresonant acoustic projector was designed, fabricated, and tested 
without significant difficulties. 
2. It met all its specifications, and it proved the principle of a mechanical projector 
whose operating depth, frequency, and amplitude of piston throw can be simultaneously or 
independently varied without incurring significant interactions among the variables: 
3. The validity of considering the nonresonant acoustic projector as a standard 
source was demonstrated. 
RECOMMENDATIONS 
1. Apply the nonresonant acoustic projector type of acoustic source to such Navy 
problems as: (a) probing and characterizing the océan’s various acoustic paths, (b) measur- 
ing effective horizontal sound speed over ocean paths of Navy interest, and (c) calibrating 
and measuring the sensitivity of the Navy’s ocean surveillance arrays. 
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2. Promptly develop the “switchable nonresonant acoustic projector” concept for 
application to significant Navy problems. 
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