Basic study on active acoustic shielding: phase 6 improving the method to enlarge AAS window-2

ABSTRACT In this paper, it was proved to be useful to use M[(1-1)-L’] FX-LMS algorism for Active Acoustic Shielding (AAS) window to enlarge the window size. The AAS is a system that can attenuate the sound passing though an open window. The AAS system is composed of many AAS cells set in an array. Each AAS cell consists of approximately colocated a microphone and a speaker. However, a size of existing type AAS window is 250mm square. Therefore, we proposed M[(1-1)-L’] FX-LMS algorism(M: number of AAS systems, L’: number of error signals used for controlling one AAS cell) for controlling a large size window and large number of AAS cells. This algorithm is a kind of FX-LMS algorithm, each AAS cell is controlled individually by it’s own reference microphone and neighboring error sensors. In the previous work, 6 AAS cells is set on rectangular window (125 x 750mm square) and controlled by 6[(1-1)-3’] FX-LMS. As a result, this system was proved to be useful for controlling AAS cells, In this paper a simulator of M[(1-1)-L’] FX-LMS algorithm was constructed, and the simulation results by 6[(1-1)-3’] FX-LMS algorithm well coincided with the above experimented results. This suggests that large AAS window feasible.