Research on effects of the sand seafloor on acoustic waves in an underwater acoustic channel

An integral expression for sound field of directional and pulsed source in shallow water with layered seafloor is derived. It is supposed that sediment and basc of seafloor are composed of water-saturated sand and solid media respectively. The values of acoustic parameters of the water-saturated sand are selected from calculating results according to the theory of porous medium model and experimental results. The synthetic full waveforms of sound pressure in the shallow water are simulated from the integral expression for sound field for the explosive point black source and directional and pulsed source. Experiments were carried out in the pool which the sediment of pool bed is composed of water-saturated sand or crystal balls: a directional transducer emits sine signal modulated by a square wave, the received waveforms were recorded at different received points.
The features of the recorded waveform envelopes are much similar to the simulated results. This result proves the model, set up by this paper, of sound propagation in the shallow water with the layered sand floor is advisable. It can predict that parameters of ocean environment effect on the waveforms received in the shallow water, so that as a reference information provided to design and process signal for underwater communication and sonar system.The attenuation and dispersion of a normal - mode are simulated for sand, uniformity liquid-state and solid-state bottom. The simulative results are compared each other so that find out the feature of the effects of the sand floor on sound wave propagation.