(19)

(11)

EP 0 555 248 A1

(12)

(43) Date of publication: 18.08.1993 Bulletin 1993/33 (21) Application number: 91918077.0 (22) Date of filing: 22.10.1991

(51) International Patent Classification (IPC):  G10K 11/ 16( . ) G10K 11/ 178( . ) (86) International application number: PCT/GB1991/001850 (87) International publication number: WO 1992/008224 (14.05.1992 Gazette 1992/11)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 29.10.1990 GB 19900023458 (71) Applicant: NOISE CANCELLATION TECHNOLOGIES, INC. Linthicum, MD 21090 (US)	(72) Inventors: ROSS, Colin, Fraser Grove House Bury Road Cambridge CB2 5BP (GB) EATWELL, Graham, Paul Cambridge CB3 7NZ (GB) (74) Representative: Stone, Patrick  28 Edenside Drive Attleborough Norfolk NR17 2EL Attleborough Norfolk NR17 2EL (GB)