Impact‐echo (IE) is an acoustic method used for nondestructive testing of concrete structures. Its principle is based on the use of longitudinal waves generated by the elastic impact of a steel sphere. However, the impact also creates other wave types such as Rayleigh and shear waves. Especially when IE is applied on structures with compact dimensions the reflections of the different wave types at the boundaries of the test object can significantly interfere with the signal. The separation of the different signal components and the definition of effective criteria to distinguish between them is therefore highly relevant. In this study a procedure based on the relation between duration and bandwidth of the different signal components is used to distinguish between the actual measurement information and interfering effects caused by reflections at the boundaries. It avoids the application of a rather complex time‐frequency analysis. This is demonstrated on simple sinusoidal signals in a first step and then applied to data collected from impact‐echo measurements. The method is also applicable to whole scan lines comprised of a large number of measurement points.

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