Since you can't ask animals how they feel, it is difficult, you have to look at what happens during and after these tests. The tests that were conducted by the Navy, were not at operational acoustic levels. Very early in the prototype phase, there was an incident in the med, involving a foreign military diver that was in the water in the western med, while the ship was operating in the eastern med, resulting in major injury. Consequently, the testing was put on hold for quite a length of time, and never operated in the med again. Later testing showed that the ping generated off of Heard Island, 53.1S, 73.5E, was received off the coast of Iceland. That is a lot of acoustic power.