SPINDEL: PHASE FLUCTUATIONS, COHERENCE AND INTERNAL WAVES 



Dr. Flatte: The integral converges. There are certain regions 

 where you have to worry about it breaking up and causing a completely 

 new ray. But you can also form criteria for that not happening. We 

 have done some work in that respect, too. 



Dr. DeFerrari: This is a problem that was in the Acoustical 

 Society several years back. Whether or not one added in a phase 

 shift of tt/4 at that point or not. This is part of that integral 

 you are talking about. I don't know whether it was ever really 

 settled or not. 



Dr. P. W. Smith (Bolt, Beranek, and Newman, Inc.): Yes, it was 

 not. (Laughter) 



Dr. Flatte: I have another question concerning the quantitative 

 comparison that you made of the phase fluctuations. How did you 

 treat the combination of several rays? There were several rays going 

 from source to receiver. Right? 



Dr. Spindel: Four rays. 



Dr. Flatte: How do you treat the combination in order to get a 

 total phase prediction for the model? 



Dr. Spindel: The total field at the receiver is simply a 

 summation of the effects of those four rays. We have computed the 

 phase at the receiving point for each of the four rays, we sum that, 

 and separate that resulting equation into an amplitude and a phase 

 factor and that is the phase. 



Dr. Flatte: So the internal wave model predicts the phase 

 fluctuation of each ray and to compare with data you perform a 

 summation of those rays? 



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