有源噪声控制次级声源的非线性建模

Nonlinearity modeling of secondary sound source in active noise control

基于电动扬声器的顺性、磁力因子和音圈自感三个非线性参数,建立了基于电力声类比线路方法的次级声源非线性时域模型。采用该模型对次级声源总谐波失真(THD)进行仿真,并与测试结果进行比较,结果表明在较低频率范围、较大输入信号幅值的情况下,该非线性模型是可行的。将该模型引入有源噪声控制系统,并以滤波-XLM S算法为例,对采用次级声源理想模型、线性时域模型和非线性时域模型的控制系统分别进行仿真,结果表明采用非线性模型系统的降噪量远低于采用其他模型的系统,并且非线性失真度大小对降噪量也具有明显的影响。

The nonlinearity of secondary sound source based on analogue circuits of electrical, mechanical and acoustical sys- tems is modeled in the time domain by considering three nonlinear parameters of electrodynamic loudspeaker including compli- ance, force factor and voice coil inductance. The total harmonic distortion （THD） of secondary sound source is simulated hy using this model and compared with the measured results. It shows that the nonlinear model is feasible while the frequency of input signal is low and its amplitude is large. This model is introduced into active noise control system, and the control sys- tems with ideal model, linear model and nonlinear model of secondary sound source in the time domain are simulated respec- tively by taking the algorithm of Filtered-X LMS for example. The results show that the system with nonlinear model has much less reduction of the noise level than the systems with other models and the magnitude of nonlinear distortion has dis- tinctive effect on the noise reduction.