[Charles bering]

Fish have no "ears" as such but a laterial line. Detects pressure changes. The bowl should effectively protect it from the pressure waves (sound) from the pipes-gimbles older would be valuable.

Doggie helmut would be important but should also have a "HANS" device as well

There IS noise canceling technology out there. Purdue U school of eng. has developed a noise canceling auto muffler 10-12 years ago that used 180 degree sound waves to help ofset (cancel) the noise. Industry has used this concept to control noise in the working enviroment. State-of-the art programable digital hearing aids are now using the technology to eliminate "feedback" in hearing aids.