WEINSTEIN: EXPLOSIVE SOUND-SOURCE STANDARDS 



Dr. Weinstein: I have to honestly answer that we don't know. We 

 don't have a set of data that would answer the question for us. We 

 have been discussing means of finding out. 



Mr. C. W. Spofford (Office of Naval Research) : I have a comment 

 for Dr. Weinstein. I am concerned with the measurements of transmission 

 loss at low signal-to-noise ratios, especially when you might have many 

 low signal-to-noise arrivals adding in the shot processor versus one 

 larger arrival yielding the same total signal-to-noise ratio. The 

 question is whether or not the accuracies of these two measurements are 

 comparable. I think there may be less accuracy in the first measurement 

 than the second, even when you appear to have 3 or 4 dB of signal-to-noise. 



Dr. Weinstein: I think it goes the other way. If you have plus 

 3 dB signal-to-noise based on the total integration, and if you look at 

 the peak of the individual arrivals and your multi-arrival structure to 

 noise, your S/N would be a lot higher. 



Mr. Spofford : I guess I'm concerned about losing arrivals down in 

 the noise even though the final transmission loss appears to have adequate 

 signal-to-noise. You may have lost the low amplitude arrivals in the 

 noise . 



Dr. Weinstein: The problem is we have noise and multiple arrivals. 

 The signal-to-noise that I am talking about is what is obtained by doing 

 a total integration over the multiple arrivals. You will obtain a lot 

 lower signal-to-noise ratio than you would obtain if you were to define 

 it based on the peak of one of your multi-path arrivals to noise background. 



Dr. J. S. Hanna (Office of Naval Research) : The question of 

 signal-to-noise ratio that I believe Mr. Spofford was getting at is not 

 the sort of thing that you get from looking at the peaks of those traces. 

 He is interested in signal-to-noise ratio in a third-octave band around 



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