根据模态声发射理论，携带大量结构或材料缺陷信息的声发射信号在结构中传播时，存在频散和多模态现象，因此声发射信号属于非平稳随机信号，利用传统的傅里叶谱分析无法有效提取声发射信号中蕴含的丰富信息。采用一种新时频信号处理方法——希尔伯特黄变换法，对频率突变的声发射信号进行了分析，显示了该方法相对其他信号分析方法的有效性和优越性。通过对薄板中的断铅信号进行希尔伯特黄变换分析，精确地获得了结构中声发射传播特性的信息。

The mass investigations of the modal acoustic emission(MAE) technology lie in analysis and processing of AE signals were proceeded. Due to every established technology of signals processing, such as FFT, power spectrum, STFT, wavelet, etc, has some shortage, the product of the signals processing is unreliable. So this paper introduced a new technology of signals processing, that is HHT, and discussed the availability and advantage of the technology. Based on the theory of the MAE, the propagation characteristics of the AE signal can be accurately conducted by analyzing the lead-breaking signal in the plate.