This communication concerns researches on the development of a new class of locally resonant acoustic materials for underwater applications (sound insulation, masking, anechoism...). Those acoustic composites are entirely synthetized thanks to soft-matter techniques and exhibit strong phenomena of multiple scattering due to embedded resonant particles in a polyurethane matrix. The resonant inclusions are made of porous-elastomeric beads whose effective elastic properties (bulk and shear moduli) are very small, as for their effective speed of sound. As a result those beads behave as low-frequency Mie-resonators. This strong local resonant scattering implies then very high levels of attenuation for the elastic waves propagating through the composite, even for small volume fraction of inclusions. Moreover the intrinsic elasticity (despite small) of the porous inclusions has less impact (less weakening) on the overall static compressibility of the composite comparatively to the case of the classical materials composed of micro balloons. This latter aspect is one of the major key-features to be improved concerning the stability of underwater acoustic coatings under static load. Experimental comparisons of the acoustic properties (under load or not) in between our new composite and the classical micro air bubble-like technology will be shown.