CIBRA is participating in the design of an acoustic experiment to be carried out with an underwater platform deployed by INFN (lstituto Nazionale di Fisica Nucleare) on the sea floor 25 km off Catania (Sicily). The platform, placed at 2500m depth, is connected by a fibre optic cable to the laboratories in Catania. The platform will host an acoustic module (to be deployed in spring 2002) with 4 broadband phones and related electronics for transmitting acoustic data (96 kHz sampling, 24 bits, 4 channels) to the coastal lab in real-time. Dedicated software will provide continuous monitoring with either continuous or scheduled recording of acoustic data. Then, through the fast INFN network it will be possible to have high speed access to the system located in Catania to get sounds for post-processing. The special design of the instrumentation will allow high sensitivity, low noise and a great dynamic range to support a series of experiments to measure the ocean noise and biological sound sources in order to evaluate the feasibility of a further INFN project, named NEMO, concerned with the detection of acoustic pulses generated by high energy neutrinos passing through water. The experiment will allow the long term study of underwater noise and of biological sound sources, fin whales and deep divers like sperm whales in particular. CIBRA is participating in the design of the acoustic instrumentation and of data processing methodologies for the classification of biological sounds, identification of man-made sounds and long term monitoring of underwater noise. One of the goals is to map the seasonal variation of sounds emitted by fin whales and sperm whales and possibly to assess their seasonal movement patterns.
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