气动式强声发生器频率特性理论分析

Theoretical Analysis of the Frequency Characteristics of an Electro-pneumatic High-intensity Acoustic Generator

建立了分析气动式强声发生器频率特性的数学模型。计算表明：信号频率比较低时气动式强声发生器位移振幅比较大，对气流的调制能力强，但高频特性差；音环的位移振幅值与音环总质量成反比；当磁感应强度B大于临界值时，在整个频率范围内，音环位移振幅随信号频率增大而变小；音环振动系统的力顺C增大，气动式强声发生器低频特性好，力顺C减小，高频特性变好；在磁感应强度和力顺选择适宜的情况下，音环位移振幅随功率放大器输出信号电压增大而增大；阻抗随信号频率变化呈现最大值。在低频段，阻抗随信号频率增大而急剧增大，在高频段则是急剧下降。

The paper sets up mathematical model for the electro-pneumatic high-intensity acoustic generator frequency characteristics analysis. The calculation indicates that, when the signal frequency is low, the sound loop displacement amplitude is large and the modulation ability of airflow is strong, the high frequency performance is poor. The sound loop displacement amplitude is in inverse proportion to the total mass. When magnetic field intensity B exceeds the critical value, the amplitude will decrease as signal frequency increases. The mechanical compliance C of vibration system increases, the low frequency performance of the acoustic generator is satisfied. As C decreases, the high frequency performance is satisfied. When mechanical compliance C and magnetic induction are chosen, the am- plitude and the output voltage of power amplifier are in proportion. The impedance has a maximum when output signal frequency varies. In low frequency, the impedance increases strongly. However, in high frequency region, it decreases rapidly originally then increases gradually. Furthermore, magnetic induction infects the impedance inversely as well.