A. Noisy platforms radiate low-frequency underwater sounds with 

 line-frequency components capable of detection at ranges of the order of 

 hundreds of miles under favorable conditions of propagation and ambient noise. 



B. Under conditions unfavorable for detection (i.e., poor propagation 

 and high ambien' noise), detection of all platforms, including the noisy ones, 

 is expected to be limited to ranges of the order' of 100 yards. 



C. 1 he existence of quiet platforms conducting both drilling and 

 production operations indicates that these systems can be engineered for 

 minimal underwater noise pollution. 



D. Accurate prediction of expected detection range will require a 

 scenario which defines (a) acoustic source spectrum for the particular 

 platform, (b) propagation conditions for the particular location and season, 

 (c) ambient noise condition as specific to sea state, ship traffic, and 

 biological noise sources in the area, and (d) species of animal involved as 

 listener. Additional data are needed on all of the above elements in order to 

 employ the source-path-receiver model effectively for accurate predictions of 

 detectability. 



E. The estimates of detection range given in this report are the 

 distances at which a mysticete whale may be expected to just detect the 

 presence of a tonal component radiated by a platform. No prediction is made 

 of animal behavior to be expected as a result of this detection. Overt animal 

 behavior may result from several considerations: 



G-35 



