WEINSTEIN: EXPLOSIVE SOUND-SOURCE STANDARDS 



the bubble-pulse period, and by variations in yield which change the 

 total energy output. 



Additionally, depth variation will alter the multipath propaga- 

 tion structure, introducing a third source of fluctuations which will 

 be dependent on the environmental details. 



During a recent experiment, SUS shots were monitored with a 

 hull-mounted transducer on the drop vessel. The data were processed 

 to determine the bubble-pulse period for approximately 700 shots 

 each at 60- and 300-foot detonation depths. 



Figure 2 shows the cumulative distribution for the 60-foot shots; 

 the bubble-pulse period at the top, the detonation depth at the 

 bottom, assuming that the yield was identical for all shots. The 

 variation in yield expected from an examination of manufacturing 

 procedures results in an uncertainty in detonation depth of about 

 ± 2 feet. As is apparent, the detonation depth varies from 50 to 

 70 feet. About 90 percent of the data points lie between 54 and 60 

 feet. For this range of detonation depths the source-level variation 

 in the 1/3-octave bands is about ± 1 dB. 



Figure 3 shows similar results for the 300-foot shots with a 

 data spread of 250 to 350 feet. About 90 percent of the data points 

 lie between 270 and 320 feet, and source-level variations of about 

 ± 1.5 dB can be expected. 



For both detonation depths source-level variations directly 

 attributable to variation in yield are estimated to be a fraction 

 of a decibel. 



These results suggest that source-level variations can be 

 corrected to within a fraction of a decibel by monitoring the shots 



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