| 摘要 |
PURPOSE:To eliminate sound leakage through a clearance, to prevent the occurrence of howling and to increase the output of a hearing aid by forming an ear type case with a soft synthetic resin which has a certain hardness range and is made of a soft vinyl chroride. CONSTITUTION:In order to obtain the ear type case 1, first an impression material such as a silicone resin, and 'GUTAPERKA(R)' is packed into each individual ear-couch or external auditory so as to obtain the impression of the inner surface of an outer ear and from the impression mold a matrix is formed with plaster, etc. The soft synthetic resin such as a soft vinyl chroride resin, a silicone resin or a polyester resin is poured into the matrix at a wall thickness having 1-2mm and is cured, thereby obtaining the ear type case 1. The most preferable hardness of the soft synthetic resin is a range from 40 deg. to 65 deg. according to JIS standard K7125A. A face plate 2 is provided with a microphone 3, a volume switch 4, a voltage case 3 serving as a power source, a gain controller 6, etc. and is formed with the hard synthetic resin such as an acrylic resin and an ABS resin having a sufficient strength. |
