CIC hearing aid seal and method of manufacturing the same

A method of manufacturing an acoustic seal (100, 110) for retaining a CIC hearing aid (30, 230) within a portion of the ear canal (10) by contact with the wall (20) of the ear canal, comprising the steps of:

• embedding sacrificial particles (70) having a size of at least 50 μm and not more than 250 μm into a silicone rubber matrix (72), wherein the concentration and the size of the sacrificial particles is selected such that a porosity of at least 40% is achieved;
• molding the silicone rubber matrix into a desired shape by using a mold and curing the silicone rubber matrix;
• removing the sacrificial particles from the silicone rubber matrix by leaching out the sacrificial particles in a solvent;
• and
• drying the silicone rubber matrix;
• wherein the seal is designed to surround at least part of the hearing aid and wherein the seal is designed, by selection of at least one of the size, the concentration, and the distribution of the sacrificial particles, to provide for an acoustic attenuation of at least 20 dB in a frequency range between 200 Hz and 6 kHz, when the hearing aid is inserted into the ear canal, and for a compliance of at least 50 mm/N.