| 摘要 |
<p>The sound output of a hearing aid is conducted along a tube to the earpiece. The end of the tube is attached, e.g. by adhesive, to a small inflated balloon which is inserted well into the ear canal. A plug, moulded to fit the ear canal opening, supports the tube and locates the balloon. Because of its internal pressure, the balloon fits closely in the ear canal. Its end surface forms a membrane across the canal and transmits sound through the intervening air space to the ear drum. The balloon material, size, internal pressure, and position in the canal are all chosen by an audiologist to suit the patient.</p> |
