MARTIN/PERRONE : GEOGRAPHICAL VARIATION OF AMBIENT NOISE IN THE OCEAN 

 FOR THE FREQUENCY RANGE FROM 1 HERTZ TO 5 KILOHERTZ 



the water column, it seems to me that with the ambient noise measure- 

 ment, we should have a simultaneous measurement of propagation so that 

 we can determine the signal-to-noise ratio as a function of the depth. 



We should do that for frequencies and for sources that are 

 located over ranges that we are concerned with and frequencies that 

 we are concerned with. 



Dr. Marshall: In all cases that I know of this morning wherein 

 data were reported, there were transmission loss runs made for their 

 own sake alone as well as for the purpose of understanding the ambient 

 noise. And, indeed, it is in general the signal-to-noise ratio 

 statistic that one really wants to use in system design and inter- 

 pretation of performance. 



Dr. Sykes: Can we ask, where did you find the best place to 

 put it? 



Dr. Marshall: That wasn't my assigned topic. (Laughter) 



Dr. Ross: 1 just want to make a comment about your Labrador 

 Sea. I think you were in an area where our statistics show about 

 400 to 600 fishing vessels and that you are not merchant ship 

 dominated in that sea as much as you are fishing boat dominated, 

 and that would explain some of this rather short-term, up-and-down 

 noise since fishing vessels have a much more sporadic movement to 

 them. 



Mr. Martin: 1 think I made that comment. Most of the fishing 

 vessels, of course, are up in the Grand Banks or that area, and you 

 can hear them all the time. The center of the basin was about 300 

 or 400 miles away. Any time you have a small number of ships, like 



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