| 摘要 |
PURPOSE:To prevent occlusion of sound duct due to water drops caused by dewing by providing a hydrophilic resin in the sound duct of the transmission route of output voice signals. CONSTITUTION:A main body 12 of a hearing aid 11 of the type hung from the ear has an amplifier and an earphone in its inside and transmits the sound to an ear plug 16 through an ear hook 13, a sound conducting pipe 14 and a coupling member 15. The sound conducting pipe 14 is formed on the overall inner wall by a hydrophilic resin 17 and the outer layer is of a double layer construction formed of synthetic resin such as vinyl chloride proper to the sound conducting tube. As the hydrophilic resin is swollen by water absorption on contacting with water the sound duct is formed of acrylic resin having high water absorbency but does not dissolve in water. It is possible to prevent water droplets produced in the transmission route of the voice signals by changes in temperature from occluding the sound duct in the transmission route. |
