| # | Country | Total Patents | |
|---|---|---|---|
| #1 | Switzerland | 3 | |
| #2 | Germany | 3 | |
| #3 | Austria | 1 | |
| #4 | Belgium | 1 | |
| #5 | Canada | 1 | |
| #6 | United Kingdom | 1 | |
| #7 | Italy | 1 | |
| #8 | Norway | 1 | |
| #9 | United States | 1 |
| # | Industry | |
|---|---|---|
| #1 | Audio-visual technology | |
| #2 | Basic communication technologies |
| # | Technology | |
|---|---|---|
| #1 | Loudspeakers and microphones | |
| #2 | Amplification control |
| # | Name | Total Patents |
|---|---|---|
| #1 | Wittkowski Johannes | 3 |
| #2 | Wittkowski J | 2 |
| #3 | Otto Hassler | 2 |
| #4 | Fischer D | 2 |
| #5 | Hasler Otto Ing | 1 |
| #6 | Fischer Detlef | 1 |
| #7 | Hueber Fritz | 1 |
| #8 | Wittkowski Johannes G A | 1 |
| #9 | Johannes Wittkowski | 1 |
| #10 | Hassler Otto | 1 |
| Publication | Filing date | Title |
|---|---|---|
| CA985182A | Directional microphone for head mounted midget hearing aids | |
| US3777079A | Directional microphone for head mounted midget hearing aids | |
| DE1277347B | Microphone for hearing aids | |
| GB1181259A | Improvements in Hearing-Aids of the kind worn on the Users' Heads | |
| DE1193105B | Electroacoustic transducer, especially hearing aid for hearing impaired devices | |
| DE1143860B | Transistor amplifier for hearing impaired devices with gain control |