The main focus of this project is on how the human central nervous system and auditory and vestibular organs are influenced by underwater shock waves and noise. This knowledge is necessary for revision of safety rules and for evaluation of new risks, like exposure from different sonar systems. A model for exposure of small animals to underwater shock waves and for evaluation of the effects on the animals was developed, tested and implemented. The shock waves were generated inside a water filled tube which, with an animal in the water, was allowed to fall down on a stone plate. The animals were under general anaesthesia and were breathing oxygen on an open system. Initial experiments, using 180 kPa shock waves, showed changes in brain activity (EEG). Biochemical parameters will also be analyzed.