有源消声中声源辐射阻抗规律的理论研究

An Impedance-Based Control System and its Application in Active Noise Control, PartⅠ: Theoretical Analysis

从声功率准则推导了两种典型消声状态 (声抑制和声吸收 )条件下 ,声源辐射阻抗的一般表达式 ,阐明了消声的物理机制 ;

To our best knowledge, there still does not exist any impedance based control system made or designed in China. We derived a general formula of radiation impedance, according to the criterion of total acoustic power output, for two reduction strategies: (1) active sound restraining, (2) active sound absorption. We expounded the energy mechanism of active noise control (ANC) with impedance explanation. In section 2.1 and section 2.2 we derived eqs.(11) through (14) for calculating radiation impedance for pulsating sources and eqs.(15) through (19) for calculating radiation resistance for directional sources separately. Figs.1 and 3 give calculated results for a numerical example. Fig.1 gives the variation of relative impedance, Z P/Z PP or Z S/Z SS , with frequency for a monopole source when the reduction strategy is active sound restraining. Fig.3 gives the variation of relative resistance, R P/R PP or R S/R SS , with frequency for a dipole source when the reduction strategy is active sound absorption.