A method for reducing the power of an acoustic primary noise signal (d m (n), m=1, 2, 3,...) at one or more control positions in a vehicle passenger compartment, the acoustic primary noise signal originating from an acoustic noise signal transmitted from a noise source through a respective primary sound path (P m, m=1, 2, 3,...) to the respective control position, the method comprising: - arranging an adaptive filter to receive input signals comprising: - an electrical reference signal (x(n)) representing the acoustic noise signal, and - at least one electrical error signal (e m (n), m=1, 2, 3,...) representing a respective acoustic signal detected by a respective sound sensor at the respective control position, - arranging the adaptive filter to provide and transmit at least one electrical control signal (y' k (n), k=1, 2, 3,...) to at least one acoustic transducer arranged in the compartment, - the at least one acoustic transducer, as a response to the at least one electrical control signal (y' k (n), k=1, 2, 3,...), providing and transmitting a respective anti-noise signal through a respective secondary sound path (S km, k=1, 2, 3,..., m=1, 2, 3,...) between the at least one acoustic transducer and the respective control position, arriving at the at least one control position as a respective acoustic secondary anti-noise signal (y m (n), m=1, 2, 3,...), such as to minimize the respective electrical error signal (e m (n), m=1, 2, 3,...), - providing a respective modelled secondary anti-noise signal (ŷ m (n), m=1, 2, 3,...) from a respective secondary sound path model (Ŝ km, k=1, 2, 3,..., m=1, 2, 3,...) - calculating a respective mean correlation coefficient (γ m (n), m=1, 2, 3,...) between the respective electrical error signal (e m (n), m=1, 2, 3,...) and the respective modelled secondary anti-noise signal (ŷ m (n), m=1, 2, 3,...), and - comparing at least one of the mean correlation coefficients (γ m (n), m=1, 2, 3,...) with at least one predefined threshold, or - comparing an average value (γ(n)) of the at least one mean correlation coefficient (γ m (n), m=1, 2, 3,...) with at least one predefined threshold. - arranging an adaptive filter to receive input signals comprising: - an electrical reference signal (x(n)) representing the acoustic noise signal, and - at least one electrical error signal (e m (n), m=1, 2, 3,...) representing a respective acoustic signal detected by a respective sound sensor at the respective control position, - an electrical reference signal (x(n)) representing the acoustic noise signal, and - at least one electrical error signal (e m (n), m=1, 2, 3,...) representing a respective acoustic signal detected by a respective sound sensor at the respective control position, - arranging the adaptive filter to provide and transmit at least one electrical control signal (y' k (n), k=1, 2, 3,...) to at least one acoustic transducer arranged in the compartment, - the at least one acoustic transducer, as a response to the at least one electrical control signal (y' k (n), k=1, 2, 3,...), providing and transmitting a respective anti-noise signal through a respective secondary sound path (S km, k=1, 2, 3,..., m=1, 2, 3,...) between the at least one acoustic transducer and the respective control position, arriving at the at least one control position as a respective acoustic secondary anti-noise signal (y m (n), m=1, 2, 3,...), such as to minimize the respective electrical error signal (e m (n), m=1, 2, 3,...), - providing a respective modelled secondary anti-noise signal (ŷ m (n), m=1, 2, 3,...) from a respective secondary sound path model (Ŝ km, k=1, 2, 3,..., m=1, 2, 3,...) - calculating a respective mean correlation coefficient (γ m (n), m=1, 2, 3,...) between the respective electrical error signal (e m (n), m=1, 2, 3,...) and the respective modelled secondary anti-noise signal (ŷ m (n), m=1, 2, 3,...), and - comparing at least one of the mean correlation coefficients (γ m (n), m=1, 2, 3,...) with at least one predefined threshold, or - comparing at least one of the mean correlation coefficients (γ m (n), m=1, 2, 3,...) with at least one predefined threshold, or - comparing an average value (γ(n)) of the at least one mean correlation coefficient (γ m (n), m=1, 2, 3,...) with at least one predefined threshold.