Number | Name | Date | Kind |
---|---|---|---|
2165123 | Ballantine | Jul 1939 | |
3396245 | Flygstad | Aug 1968 | |
3659056 | Morrison et al. | Apr 1972 | |
4912769 | Erbe | Mar 1990 | |
5010575 | Marutake et al. | Apr 1991 |
Number | Date | Country |
---|---|---|
0300748 | Dec 1989 | JPX |
Entry |
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Omni Hearing Systems, "Model X312A", Dec. 1990. |