CHRISTIAN: THE ACOUSTIC OUTPUT OF EXPLOSIVE CHARGES 



of the problems can be removed if we want to pay the price: if we 

 want to set stringent limits on SUS charge detonation depth toler- 

 ances, for example, or require high quality on-site measurement of 

 charge output for each shot in a series. But such prices are high. 

 I would like to suggest that there may be a better way out, a way that 

 will involve some possibly painful changes over the short term, but 

 will pay off handsomely over the long term. Why not work toward a 

 sensible matching of explosion sources and processing methods? Does 

 a SUS charge always have to be matched to 1/3-octave bands? 



An explosion has an "inherent bandwidth," as it were, in its 

 bubble fundamental. If analysis bandwidths were selected to be at 

 least two or three times as wide as the bubble harmonics, much of the 

 variability I have been discussing will be washed out. On the other 

 hand, if the practical acoustics problem being attacked includes an 

 important fixed recording bandwidth which is controlling, then per- 

 haps we should design a charge to match the problem, not just pick 

 the one that comes easily to hand. In short, I am suggesting we 

 should try Figure 14. 



To summarize: if explosion source levels in 1/3-octave (or 

 narrower) bands must be predicted to within 1 dB over the frequency 

 range of 10 to 300 Hz, then: 



1) Our present state of knowledge is not adequate. 



2) We must acquire new data with controlled experiments. 



3) We must improve our source level models. 



4) Recording and processing methods must be re-examined. 



5) Shallow sources need special attention. 



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