An acoustic protection cover for encapsulating a motor vehicle component, the cover including: a based on injection-molding material, the material comprising a thermoplastic matrix and a filler that is dispersed in such a way as to exhibit a density of between 1.3 and 1.6, the shell comprising two half-shells delimited by a thin region originating from the molding and forming a flexible hinge; a layer of elastically compressible foam overmolding the internal face of the shell, so that the cover forms an insulation system of the “mass-spring” type, the mass being formed by the shell and the spring by the layer; a means of holding the half-shells together once the hinge has been folded, so as to allow the component to be encapsulated, the matrix being made of polyvinyl butyral (PVB) and the level of filling being less than or equal to 50% by mass of the material.