Acoustic detection of ultra-high energetic neutrinos: A snap shot

Already more than 30 years ago the acoustic particle detection method has been considered to be one possibility to measure signals from ultra-high energetic neutrinos. The present status and problems of corresponding model predictions are discussed in comparison with existing experimental measurements. Available acoustic sensors and transmitters are described and new ideas for corresponding applications are mentioned. Different methods for in situ calibrations are discussed. Results of measurements of acoustic test arrays at different sites are presented in some detail. Future activities for applications of the technology in large size detectors are evaluated.