HANNA: DESIGN OF TRANSMISSION LOSS EXPERIMENTS 



Source Level Errors 



Errors in the calibration of the source will directly affect the 

 inferred reflectivity. Worse, variations in the spectrum level of 

 the source from event to event will induce point-to-point errors in 

 the estimates of reflectivity. When pressing to get meaningful values 

 of reflectivity to accuracies of a few dB, it is obvious that all 

 measured or estimated qualities entering the computations must be 

 known to accuracies consistent with that desired in the result. Con- 

 cerns expressed elsewhere in these proceedings regarding measured 

 source levels for explosives have serious implications for measure- 

 ments, such as those here, which rely on absolute source levels. 



CONCLUSION 



This paper has attempted to develop a particular approach to the 

 design of transmission loss measurements based upon the use of exist- 

 ing acoustic models to estimate the nature of the loss in advance. 

 Examples were presented to illustrate common pitfalls which can be 

 avoided with this approach. 



REFERENCES 



Hanna, J. S., and B. E. Parkins, "Some considerations in choosing an 

 explosive source and processing filter for the measurement of 

 transmission loss," J. Acoust. Soc . Am. 56, 378-386, 1974 



539 



