Patent ID: 7957542

Claim:
An adaptive beamformer unit comprising: a filtered sum beamformer for processing input audio signals (u 1 , u 2 ) from an array of respective microphones, and for forming, as an output, a first audio signal (z) predominantly corresponding to sound from a desired audio source by filtering, with a first adaptive filter (f 1 (-t)), a first one of the input audio signals (u 1 ) and by filtering, with a second adaptive filter (f 2 (-t)), a second one of the input audio signals (u 2 ), the coefficients of the first filter (f 1 (-t)) and the second filter (f 2 (-t)) being adaptable with a first step size (α 1 ) and a second step size (α 2 ), respectively; noise measure derivation means for deriving, from the input audio signals (u 1 , u 2 ), a first noise measure (x 1 ) and a second noise measure (x 2 ); and an updating unit for determining the first and the second step size (α 1 , α 2 ), respectively, with an equation comprising, in a denominator, the first noise measure (x 1 ) for the first step size (α 1 ) or the second noise measure (x 2 ) for the second step size (α 2 ), respectively.