单环螺线差分麦克风阵列结构及性能研究

The Structure and Performance Study of Single-Loop Spiral Differential Microphone Array

基于雅可比展开法设计的圆环型差分麦克风阵列,可产生频率不变的空间响应和调向到任意方向的波束图,但受贝塞尔函数在某些特定频率取零值的影响,白噪声增益和指向性因子会出现零陷问题,导致麦克风阵列性能恶化。同心圆环麦克风阵列可以消除零陷问题,但需要的麦克风单元数量较多,且阵列分布面积也较大。设计一种基于阿基米德螺线结构的单环螺线差分麦克风阵列。对比分析了该阵列与圆环型差分阵列在白噪声增益、指向性因子和波束图方面的差异。讨论了螺线参数选取对其性能的影响。仿真结果表明,在同等条件下,单环螺线差分阵列克服了圆环型差分阵列的白噪声增益,和指向性因子在某些特定频率点出现的零陷问题,在不增加麦克风数量的情况下,表现出更优越的性能。随着麦克风数量的增加,阵列形成的波束性能得到进一步改善。

This paper investigates a single-loop spiral differential microphone array,engineered based on the Jacobi-Anger expansion.The circular differential microphone array it employs is capable of generating a frequency-invariant beampattern that can be steered in any direction.However,this array faces performance deterioration due to the zero value of the Bessel function at specific frequencies,leading to nulls in white noise gain and directivity factor.The concentric circular microphone array,while addressing these nulls,requires a larger number of microphones and a more extensive array distribution area.We propose a single-loop spiral differential microphone array,structured on the Archimedes spiral.The study compares and analyzes differences in white noise gain,directivity factor,and beam pattern between the proposed array and the conventional circular differential array.The impact of spiral parameters on the array’s performance is also examined.Simulation results demonstrate that the single-loop spiral differential array mitigates the issues of deep nulls in white noise gain and directivity factor at certain frequencies,observed in the circular differential array.This is achieved without increasing the microphone count,showcasing superior performance.Furthermore,as the number of microphones increases,the array’s beamforming performance is progressively enhanced.