|
| US4473130 | 30 sept. 1982 | 25 sept. 1984 | Hauni-Werke Korber & Co. Kg. | Crash helmet with communication system |
| US4901356 | 18 déc. 1987 | 13 févr. 1990 | Actron Manufacturing Company | Voice transmission system |
| US5138666 | 9 sept. 1991 | 11 août 1992 | Actron Manufacturing Company | Voice transmission system |
| US5371804 | 15 nov. 1991 | 6 déc. 1994 | Actron Manufacturing Company | Voice transmission system |
| US5428688 | 29 mars 1993 | 27 juin 1995 | Audiopack Sounds Systems | Voice transmission system with remote microphone |
| US5463693 | 10 nov. 1993 | 31 oct. 1995 | Audiopack Sound Systems Inc. | Voice amplification adapter assembly for face mask |
| US5533131 | 23 mai 1994 | 2 juil. 1996 | | Anti-eavesdropping device |
| USD297234 | 20 oct. 1986 | 16 août 1988 | Pregaphone Inc. | Fetal communication device |