| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that, when acoustic transmission characteristics change, it is difficult to grasp that based upon a gain margin and a phase margin up to divergence of an adaptive filter, and a value of a step size parameter, used by LMS algorithm, which is sufficiently small is therefore experimentally or experientially determined while given a margin. <P>SOLUTION: An active noise reduction device is configured to include a determination unit which finds step size parameters μ satisfying the following expression each for a sampling frequency of the adaptive filter and a discrete frequency determined by the number of filter coefficients and determines the minimum value of the parameters. In the following expression, X is a value obtained through Fourier transformation of a reference signal, ¾X¾<SP POS="POST">2</SP><SB POS="POST">ave</SB>is a time average value of the sum of the square of the real part of X and the square of the imaginary part, Rc^ and θc^ are the gain and phase of simulation acoustic transmission characteristics, and Rc' and θc' are the gain and phase of the acoustic transmission characteristics having changed from an initial state. <P>COPYRIGHT: (C)2012,JPO&INPIT |
