Patent ID: 6845162

Claim:
A device for active sound control in a space ( 2 ) with a sound field from at least one sound source ( 3 ), comprising at least one pulse sensor ( 5 ), which is arranged to provide a pulse signal (t(n)) having a frequency which varies with a state of operation of said sound source, a detecting member ( 6 ), which is arranged to detect the phase and the frequency of said pulse signal (t(n)), a number (K) of sound influencing members ( 8 ), which are arranged to reduce the sound field in said space, a number (M) of sound sensors ( 9 ), which each is arranged to sense the actual sound field in said space ( 2 ) and provide an error signal e m (n), and a control unit ( 7 ), which includes a signal supply device ( 11 , 12 ), which is arranged to receive the pulse signal (t(n)) and supply a first signal (x(n)) to an adaptive filter ( 15 ) of the control unit ( 7 ), which has a number of filter coefficients (w k ) and is arranged to generate, from the first signal (x(n)), a drive signal (y km (n)) for each sound influencing member ( 8 ), and a set of second signals (x′ km (n)) to a calculating member ( 24 ), which is arranged to calculate an updating of said filter coefficients (w k ) by means of said second signals (x′ km (n)) and the error signals (e m (n)) and to update the adaptive filter ( 15 ), characterised in that the signal supply device ( 11 , 12 ) includes at least one coefficient table ( 21 ), which is arranged to provide a first set of amplitude coefficients (ρ) and a second set of delay coefficients (θ′) for generating said second signals (x′ km (n)) from detected phase and frequency of the pulse signal (t(n)), wherein said first set of amplitude coefficients (ρ) are related to the amplitudes (ρ) of said second signals (x′ km (n)) and said second delay coefficients (θ′) define phase relations between the pulse signal (t(n)) and said second signals (x′ km (n)).