Samejima Toshiya
Department of Acoustic Design, Kyushu Institute of Design, 4-9-1, Shiobaru, Minami-ku, Fukuoka 815-8540, Japan.
J Acoust Soc Am. 2003 Mar;113(3):1483-91. doi: 10.1121/1.1538197.
In this paper, a new control system in which the acoustic impedance of an electro-acoustic transducer diaphragm can be actively varied by modifying design parameters is presented and its effectiveness is theoretically investigated. The proposed control system is based on a state-space description of the control system derived from an electrical equivalent circuit of an electro-acoustic transducer to which a differentiating circuit is connected, and is designed using modem control theory. The optimal quadratic regulator is used in the control system design, with its quadratic performance index formulated for producing desired acoustic impedance. Computer simulations indicate that the acoustic impedance of the diaphragm can be significantly varied over a wide frequency range that includes the range below the resonance frequency of the electro-acoustic transducer. A computer model of the proposed control system is used to illustrate its application to semi-active noise control in a duct. It is demonstrated that the proposed control system provides substantial reductions in the noise radiating from the outlet of the duct, both in the stiffness control range and in the mass control range.
本文提出了一种新型控制系统，通过修改设计参数可主动改变电声换能器振膜的声阻抗，并对其有效性进行了理论研究。所提出的控制系统基于从连接了微分电路的电声换能器的等效电路导出的控制系统的状态空间描述，并采用现代控制理论进行设计。在控制系统设计中使用了最优二次调节器，其二次性能指标用于产生所需的声阻抗。计算机模拟表明，振膜的声阻抗可以在很宽的频率范围内显著变化，包括电声换能器共振频率以下的范围。所提出的控制系统的计算机模型用于说明其在管道半有源噪声控制中的应用。结果表明，所提出的控制系统在刚度控制范围和质量控制范围内都能显著降低从管道出口辐射的噪声。
