Bionic hearing doesn't age, although external parts sometimes need replacement.

仿生听觉不会随年龄增加而退化，尽管某些外部配件有时需要更换。

So we didn't want any external moving parts.

所以我们不需要任何外部活动部件。

Modifications in hard parts and in external parts sometimes affect softer and internal parts.

硬部件和外部部件的修改有时会影响较软的部件和内部部件。