Patent ID: 6888949

Claim:
A noise reduction system for a sound reproduction system, in particular for hearing aids, comprising: a primary microphone outputting a first signal in response to received speech signals and received noise signals; a secondary microphone outputting a second signal in response to said received speech signals and said received noise signals; a first signal processing section comprising: a first signal delaying means, wherein said first signal is input into said first signal delaying means; a fixed filter, wherein said second signal is input into said fixed filter; and a first summing function, wherein a first signal delaying means output is subtracted from a fixed filter output by said first summing function to produce a noise reference signal; and a second signal processing section comprising: a second signal delaying means, wherein a speech reference signal output by said first signal processing section is input into said second signal delaying means; an adaptive filter, wherein said noise reference signal is input into said adaptive filter, wherein said adaptive filter has an adaptive mode of operation and a non-adaptive mode of operation, and a second summing function, wherein an adaptive filter output is subtracted from a second signal delaying means output by said second summing function to produce an output signal with an improved signal-to-noise ration, and wherein said adaptive filter operates in said non-adaptive mode of operation when speech dominates said output signal and operates in said adaptive mode of operation when speech does not dominate said output signal.