Fast Convergence Active Noise Control System Using Single Adaptive Filter with a Whitening Function of Noise Source Signal

It has been shown that it is possible to construct an ideal ANC system in which the noise source signal is a white signal by applying a dither signal having a power spectrum that is the inverse of the noise source signal. The noise source signal is a random signal that has reached to the microphone via the plural number of long distance acoustic paths. Therefore, the deviation of the frequency characteristic of the power spectrum is considered to be large. The nature of the system that the noise source signal is equivalently replaced by a white signal is extremely significance. The main aim of the paper is to verify the basic principle of this high speed ANC system to the actual noise. A method of generating an external dither signal with a power spectrum that is in reciprocal relation to the power spectrum of the noise source signal is discussed. Also, a practical normalized adaptive algorithm and a range of stable step size are derived. Finally, numerical verifications with actual noise source signal is performed by computer simulation, and the features and effectiveness of the proposed system are summarized.