Method of fabricating hollow spheres, hollow spheres obtained thereby, and a sound absorber device making use thereof

A method of fabricating hollow spheres suitable for use in sound-absorber devices, the method comprising:

• preparing cores of material that melts or decomposes when heated;
• placing the cores in a mixer and covering them therein with a liquid binder based on polymeric compounds suitable for cross-linking under the effect of temperature;
• preparing a first powder material in the form of an organic powder or of a metal or mineral powder or of fibers;
• preparing a second powder material that is decomposable by heat and/or soluble in a solvent in which the first powder material and the binder are not soluble;
• mixing said first and second powder materials and adding them into the mixer;
• drying the resulting coated cores;
• and
• baking the coated cores at a temperature that causes the material constituting the cores to melt or decompose, causing the polymeric compounds of the binder to cross-link so as to obtain hollow spheres having porous and perforated walls.