Dr. Mascarenhas, One more new reference can be found in the October 2007 issue of Marine Mammal Science. It is an interesting paper that goes into a lot of analytical work on gas bubble growth and exchange as it relates to their dive profiles, etc.. It is more about beaked whale diving physiology and behavior than sonar specifically, but it is all related to causes of apparent beaked whale susceptibility to sonar. Zimmer, W. M. X., Tyack, P. L. 2007. Repetitive Shallow Dives Pose Decompression Risk in Deep-diving Beaked Whales. Marine Mammal Science. 23(4): 888-925 Hope this helps, Alex Costidis