The three ambient noise conditions are: 



High Noise: Sea state 6, heav\' shipping 

 Moderate: Sea state 2, moderate shipping 

 Low: Sea state 0, light shipping 



These three conditions span tho essential variability of 

 expected arnbient noises, and so should give a good estimate of the range in 

 minimum detectable signal levels to be expected. The MDS levels for the three 

 ambient noise conditions and appropriate critical ratios are given in Tables 

 1, 2, and 3 in the frequency columns representing the components of each 

 source. 



In the absence of an exhaustive analysis of the various OCS 

 sites, it would appear that the moderate case, represented by sea state 2 and 

 moderate shipping might be most representative of OCS areas in general. The 

 high noise conJition would be expected in areas near major ports and shipping 

 lanes during high winds, and the low noise condition would occur at locations 

 remote fror. shipping such as certain Alaskan waters during periods of calm 

 winds. It should be pointed out that the three combinations of sea state and 

 shipping density listed above were selected to demonstrate the dependence of 

 detection distance on the noise generation parameters. The sea state 6, 

 heaving shipping, represents the highest noise background likely to be 

 encountered by a listening animal, while the sea state 0, light shipping, 

 represents a minimal background condition. It must be emphasized that, in 



G-30 



