中文摘要：

针对参量声源自解调信号失真问题，根据“Berktay远场解”对其进行了理论分析，并通过实验对理论分析结果进行了验证，发现：“Berktay远场解”对自解调信号中的基频、差频可以较准确地预测，而对导致信号失真的主要因素如二次谐波、和频等的预测误差很大，不能作为失真分析的精确依据；差频不是导致参量声源自解调信号失真的主要原因，降低失真的有效途径是减小自解调信号中二次谐波、和频分量，从而使有害频率成分的数量及幅值得到有效抑制。本项研究揭示了导致参量声源自解调信号失真的主要因素及其变化规律，可为参量声源信号处理方法的研究提供有益参考。

英文摘要：

The distortion problem of the self-demodulated signal of parametric sound source is analyzed theoretically according to the ＂Berktay far-field solution＂, and the theoretical analysis result is verified with some related experi- ments. The results show that the ＂Berktay far-field solution＂ can predict the fundamental frequency and difference frequency at an acceptable precision;but for the main factors that cause signal distortion, such as second-order har- monic wave and sum-frequency wave, the prediction errors are too large to be accepted, which means that the ＂Berk- tay far-field solution＂ can not be used as the theoretical basis for analyzing the distortion. The difference frequency signal is not the main factor causing the distortion of the self-demodulated signal of parametric sound source ; and the effective approach to reduce the distortion is to reduce the second-order harmonic and sum-frequency components, which can suppress the quantity and amplitude of the harmful frequency components effectively. This study reveals the main factors contributing to the self-demodulated signal distortion and their varying rule, which can provide a helpful reference for investigating the signal processing methods of parametric sound source.