本研究使用主動式噪音控制理論來探討論三維方形剛性封閉聲場之聲場模態激振的設計與控制問題。因此本文使用推導出的聲場方程式，以LMS矩陣方法將其轉換成主動控制形式，經由最佳化控制理論求出多點的主動控制方程式，並撰寫程式，以模擬出主動控制前與控制後的情形。最後在所得最佳控制音源體積速度下，整理出聲場模態激振之設計與控制的方法。 研究結果得知要得到較少的模態激振與較小的振幅必須將音源點靠近聲場的中心，所以較有效的控制是將控制音源靠近聲場的角落。在控制低頻的振幅時，若將控制音源越靠近主要音源的話則可得到較好的振幅控制效果。 The modal design and control problem of three dimensional rigid close space is investigated by the theory of active noise control in this paper.The active control equation for multiple point is derived from the wave equation by using the optimal control theory and LMS method.The potential energy of sound field with and without active control can be found by calculating the optimal control source volume velocity.The results show that the less modes with small amplitude can be excited by the source near the center of the acoustic field.Therefore the effective control can be obtained by using the control source near the corner of the acoustic field.To control the low frequency modal amplitude ,the control source can near the primary source as close as possible.
