In this paper we present some results from Brillouin scattering measurements on lecithin-based gels. The normalized hypersound absorption data give clear evidence of the establishement of an extended network at temperatures lower than 25-degrees-C, when the micelle size reaches a threshold value. The transition between the two regions is interpreted as originated by a delicate balance between the breaking and re-forming mechanisms of the micelles and the system polydispersivity on which the collisional effects play the main role.