**MAREE has designed simulations tools concerning underwater acoustic propagation, reverberation and ambient noise. Applications concerns sonar performance prediction, help for new Modem design, mapping of expected noise …**

**Ambient noise:**

Simulation can be used to predict ambient noise by means of models that take in account with environmental features of a given area. It is therefore possible to evaluate noise variability versus input parameters .

**Propagation:**

Propagation features of an acoustic waveguide are given by the impulse response. In general, this is done by means of ray theory. In practice, a dichotomic method is used to compute eigenraies. A spectrum is associated with each ray and the complete temporal signal is then given by inverse Fourier transform. It is therefore necessary to provide an environment, a geometry and the signal specifications to establish the impulse response.

**Reverberation:**

Reverberation prediction is necessary to simulate the signal received by a Sonar. It consist in computing parameters of the ray tube. Volume, surface and bottom functions are then calculated along each ray tube. It is therefore possible to evaluate the response corresponding to a particular emitted signal.

**Signal processing:**

From these calculus, it is possible to generate a simulated signal corresponding to the signal that would be recorded in real conditions.