球形传声器阵列脉冲响应测量的非线性失真分析

Analysis of Nonlinear Distortion in Impulse Response Measurement of Spherical Microphone Array

在球形传声器阵列的脉冲响应测量中,其几何结构对入射声波产生散射作用,使各传声器检拾信号中声源非线性失真的谐波比例发生变化.文中选取以最大长度序列以及正弦对数扫频为激励声源的两种脉冲响应测量方法,通过仿真和实际测量评估非线性失真对其测量结果的影响.仿真和测量结果表明,由于声波在球面散射的作用,谐波成分将随入射声波角度而产生变化;声源谐波失真阵列背对声源的传声器对输出影响较小,而面对声源的传声器对输出影响较大;总体上最大长度序列测量法对声源的非线性失真更为敏感,对数扫频方法更适于球形传声器阵列的脉冲响应测量.

During the impulse response measurement sound wave caused by the array geometry may change of spherical microphone arrays, the scattering of the incident the harmonic proportion of signals recorded by the microphone. In this paper, two methods, one using the maximum length sequence and the other using the logarithmic sine sweep as the excitation source, were adopted to measure the impulse response, and the effect of nonlinear distortion on the measured results was analyzed. Moreover, a simulation was carried out for comparison. Simulated and measured re- suits indicate that （ 1 ） the proportion of harmonic distortion varies with the incident angle of sound source due to the scattering of incident sound wave on the spherical surface; （2） the microphone with a harmonic distortion array back onto the sound source slightly affects the output, while the microphone with a harmonic distortion array facing to the sound source greatly affects the output; and （3） in general, the measurement method based on the maximum length sequence is more sensitive to the nonlinear distortion of sound sources while the method based on the logarithmic sine sweep is more suitable for the impulse response measurement of spherical microphone arrays.