用常规超声脉冲反射法对固体内薄夹层的检测是一个较为难以解决的课题,我们用超声频谱法对此课题进行了实验研究和理论分析.结果表明:1 有薄夹层的反射回波频谱将出现缺口,缺口频率刚好对应薄层的厚度共振频率;2 缺口下陷深浅由薄层反射率所决定.因此,通过反射回波缺口频率和缺口下陷深浅的测量,有可能为探测薄层的厚度和其性质提供一种有意义的方法. Using conventional ultrasonic pulse reflection method for the detection of solid interlayer is a difficult problem to be solved, we have carried out experimental research and theoretical analysis on this subject by using ultrasonic spectroscopy.The results show that: 1 The reflection echo spectrum with thin interlayer will be The gap frequency corresponds exactly to the thickness resonance frequency of the thin layer; 2 The depth of the notch sag is determined by the reflectivity of the thin layer. Therefore, by measuring the reflection echoes’ notch frequency and the notch sag, it is possible to measure the thickness of the thin layer Its nature provides a meaningful method.