声发射（英语：Acoustic emission）：由于材料内部结构发生变化而引起材料内应力突然重新分布；使机械能转变为声能；产生弹性波，称为声发射。声发射的频率一般在1KHz-1MHz之间。

材料内部结构发生变化的原因有如下几种可能：

材料出现声发射，大部都会引起危害。因此，监测材料，包括金属、陶瓷、复合材料、岩石、混凝土及制作过程的声发射是很重要的

声发射广泛用于以下几种工业：

声发射技术和其它非破坏检测技术不同之处是：声发射检测的是材料内的情况；而一般非破坏检测则重视材料内的结构。

Acoustic emission (AE) is the phenomenon of radiation of acoustic (elastic) waves in solids that occurs when a material undergoes irreversible changes in its internal structure, for example as a result of crack formation or plastic deformation due to aging, temperature gradients or external mechanical forces. In particular, AE is occurring during the processes of mechanical loading of materials and structures accompanied by structural changes that generate local sources of elastic waves. This results in small surface displacements of a material produced by elastic or stress waves generated when the accumulated elastic energy in a material or on its surface is released rapidly. The waves generated by sources of AE are of practical interest in the field of structural health monitoring (SHM), quality control, system feedback, process monitoring and others. In SHM applications, AE is typically used to detect, locate and characterise damage.