for OCS development, (c) they are believed to have very sensitive hearing in 

 the low frequency region in which oil platforms have been found to produce 

 high noise levels. The odontocetes, on the other hand, also have sensitive 

 hearing, but it is mainly employed at high frequencies, generally above those 

 emitted from the oil platforms in data obtained from studies up to this time. 

 This, together with the directional sound discrimination capability of most 

 odontocetes suggests that they are least likely !;o be affected adversely by 

 oil platform noise. 



For the purpose of this report, the receiver is assumed to be a 

 mysticete (baleen) whale. At this point it is probably not necessary to 

 select a particular single species (bowhead, gray, humpback, etc.), as the 

 available data on the hearing of any specific species is minimal. In order to 

 predict the threshold of audibility of sounds it will be necessary to make a 

 number of assumptions regarding the whales' hearing. In the main, these 

 assumptions follow those of Payne and Webb (1971) in their paper on acoustic 

 signaling by baleen whales. 



G-22 



