Abstract
The active sound absorbing device unit of the transmission noise through a thin plate using a plate plane-wave speaker as the secondary sound source was developed and its lightening and compacting construction methods of elements was examined by trying the various combinations of elements. The controller is designed on the basis of the Filtered-x LMS adaptive algorithm by using DSP under the condition that the thin plate is subjected to the band-limited white noise. It was verified by the actual control experiments that the improvement from the view-point-of lightening of the unit is attained as a whole by the passive insulation effect of the speaker elements in addition to the active sound absorbing effect in comparison with the case in which a plane-wave speaker consisting of the piezoelectric film was used.
