中文摘要：

阻抗梯度变化介质是从多层复合介质领域脱颖而出的一种声学介质，它是通过选取具有不同特征阻抗的材料，从阻抗匹配的角度组成特性阻抗成梯度变化的介质，从而获得更好的声学性能。针对水中声学介质的声传播问题，建立了阻抗梯度变化介质中的声传播模型，对其声学特性进行了研究，推导了阻抗梯度变化介质的反射、吸声系数的计算公式。通过仿真计算，将阻抗梯度变化介质与传统均匀介质的声学性能相对比，讨论离散计算中介质层数的选取原则。制备了阻抗梯度变化介质，进行了水下声学性能测量实验，实验结果表明：实验介质的阻抗具有良好的连续性分布能够满足实验要求，测量结果验证了阻抗梯度变化介质更小的反射系数和更大的吸声系数，为阻抗梯度变化介质在水声工程中的应用提供了理论依据。

英文摘要：

The media with gradient change of impedance is an acoustic media which is developed from multiple layer media.Using the principle of impedance matching method, better acoustic properties based on the media with gra-dient change of impedance with different characteristic impedance of materials can be obtained.Applying this media to underwater acoustic engineering, the model of acoustic propagation in the media was established and the sound properties were investigated.The calculation formulas for the reflection and sound absorption coefficients of the media with gradient change of impedance were derived.Numerical simulations were also conducted.The acoustic properties of the media with gradient change of impedance were compared with traditional homogeneous media.The rules of the number of layers were discussed.The media with gradient change of impedance were prepared and the experiments in a pulse acoustic tube were carried out.The experimental results showed that the preparation media with continuous distribution of impedance can meet the need of experiment.The measure results verified smaller re-flection coefficient and larger absorption coefficient of the media with gradient change of impedance, which provide a theoretical basis for the application of the media with gradient change of impedance in acoustic engineering.