As another former surface and sub sonar tech out of San Diego, you would probably have to agree this is a rediculous concern. Reason I say this is when on the CG, we used Dolphins for target practice qualifications. I would think that and others like throwing freon filled units off the side of the ship are much larger concerns than damaging dolphin or whale hearing. I just bet in the last ten years this has not changed one bit since I got out.
My senior cheif used to encourage us to 'open up' when whales would slam upside the sub outside Alaska. You dont just make them deaf, you melt their insides when you do that. So make them deaf???!!! I think this should be peoples last concern.