Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6507659 | Microphone apparatus for producing signals for surround reproduction | Roger S. Keller | 2003-01-14 |
| 4670709 | Portable audio system and audio cable continuity tester | — | 1987-06-02 |