(19)

(11)

EP 0 643 571 A1

(12)

(43) Date of publication: 22.03.1995 Bulletin 1995/12 (21) Application number: 92913616.0 (22) Date of filing: 05.06.1992

(51) International Patent Classification (IPC):  A61F 11/ 14( . ) G10K 11/ 178( . ) (86) International application number: PCT/US1992/004569 (87) International publication number: WO 1993/025167 (23.12.1993 Gazette 1993/30)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU MC NL SE (71) Applicant: NOISE CANCELLATION TECHNOLOGIES, INC. Linthicum, MD 21090 (US)	(72) Inventors: EATWELL, Graham Annapolis, MD 21401 (US) EVANS, Robert Baltimore, MD 21234 (US) HOHMAN, John Towson, MD 21204 (US) SCOTT, Roy Columbia, MD 21044 (US) (74) Representative: Dauster, Hanjörg, Dipl.-Ing., et al  WILHELM & DAUSTER Patentanwälte Hospitalstrasse 8 D-70174 Stuttgart D-70174 Stuttgart (DE)