组合声源管路信号失真的自适应修正方法研究

Research on adaptive correction method of signal distortion of combined sound source pipeline

针对使用外置声源模拟汽车进气、排气噪声进行空气声传递路径分析的试验中,现有低频声源无法发出进排气时频率为30 Hz的低频噪声,同时由于低频声源体积过大需要过渡管道才能将噪声信号传输至排气尾管。为了解决声源系统引入过渡管道带来的声阻抗变化,提出了一种自适应预滤波的噪声修正方法。该方法采用最小均方误差自适应算法对系统逆传递函数进行拟合,得到最佳滤波器系数,通过构建有限脉冲响应滤波器实现对组合声源系统信号失真的修正。仿真结果表明,与维纳滤波方法相比,该方法实现了信号在30~1000 Hz频段范围内±5 dB的幅值波动,管口噪声信号输出稳定。基于NI Compact RIO搭建了滤波器并进行测试,试验的噪声频谱曲线与仿真结果吻合度较高,证明了该方法的有效性。

In the airborne sound transmission path analysis experiment,an external sound source is used to simulate car intake and exhaust noise.However,the existing low-frequency sound source cannot emit the 30 Hz low-frequency noise such as intake and exhaust,and the volume of the low-frequency sound source is too large,so that a transition pipe is needed to transmit the emitted noise signal to the exhaust tail pipe.In order to solve the problem of acoustic impedance changes caused by introducing transition pipe into the sound source system,an adaptive pre-filtering noise correction method is proposed.This method uses the minimum mean square error adaptive algorithm to fit the inverse transfer function of the system to obtain the best filter coefficients.The finite impulse response filter is constructed to correct the signal distortion of the combined sound source system.The simulation results show that,compared with the Wiener filter,this method realizes a signal amplitude fluctuation of±5 dB in the range of 30~1000 Hz,and the signal output of the nozzle is stable.The filter is built and tested based on NI Compact RIO.The tested result of noise spectrum curve is in good agreement with the simulated one,which proves the effectiveness of the method.