Issued Patents 1989
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4879750 | Hearing aid with cerumen trapping gap | — | 1989-11-07 |
| 4840249 | Apparatus for srewing a cover onto a screw neck of a hearing aid | Ulrich Birkholz, Christof Haertl | 1989-06-20 |
| 4834927 | Method and apparatus for producing an ear impression | Ulrich Birkholz, Christof Haertl | 1989-05-30 |