Title:
BACKGROUND-NOISE REDUCTION
Kind Code:
A1


Abstract:
Abstract not available for EP1169696
Abstract of corresponding document: WO0055846
Interference by siren background-noise with speech transmitted from radio equipment (3) of an emergency-service vehicle, is reduced by apparatus (1) that subtracts (43) an estimate nk of the correlated siren-noise component from the contaminated signal yk supplied by the cab-microphone (2). The estimate nk is computed by FIR (finite impulse response) filtering of a siren-reference signal xk supplied by a unit (4) from one or more microphones located on or near the siren, or from the electric waveform driving the siren. The filter-coefficients wk are adjusted according to an LMS (least mean square) adaptive algorithm that is applied to the correlated-noise component ek of the fed-back noise-reduced signal, so as to bring about iterative cancellation with close frequency-tracking, of the siren noise.



Inventors:
Townsend, David Mark (GB)
Sherratt, Robert Simon (GB)
Application Number:
EP20000909478
Publication Date:
01/09/2002
Filing Date:
03/10/2000
Assignee:
FULCRUM SYSTEMS LTD (GB)
International Classes:
G10L21/0208; (IPC1-7): G10L21/02
European Classes:
G10L21/02A1
View Patent Images:
Other References:
See references of WO 0055846A1
Attorney, Agent or Firm:
Coles, Graham Frederick (Graham Coles & Co. 24 Seeleys Road, Beaconsfield, Bucks. HP9 1SZ, GB)