TRANSDUCER DIRECTED DOWNWARD 



287 



100 



500 



1000 



5000 



-150 



-130 



-150 



-130 



-150 -130 



REVERBERATION LEVEL R', IN DB 

 Figure 7. Observed volume reverberation levels versus scattering depth; GB units; sound beam vertical. 



of the volume-scattering coefficient. It also appears 

 from Figure 12 that the scattering coefficient is not 

 affected in the same way at all frequencies by changes 

 in position. These results, if verifiable, also substanti- 

 ate the hypothesis that volume reverberation is not 

 an intrinsic property of water as such, but results 

 from scatterers in the ocean whose number and type 

 are affected by oceanographic and climatic condi- 

 tions. Certainly, if reverberation were a property of 



water as such, it is difficult to see how small changes 

 in position could result in the different shapes ob- 

 servable in the curves of Figure 12. 



Figure 13 shows the mean values of 10 log M 

 averaged at each frequency over all the positions of 

 Figure 12 and plotted as a function of frequency. 

 The vertical lines in Figure 13 represent mean devia- 

 tions from this average of the values plotted in 

 Figure 12. Figure 13 shows that, on the average, there 



