One way to look at it is that the modes of the system are nothing more than a very elaborate set of filters which have the ability to amplify and attenuate an input signal on a frequency basis.

看待这个问题的一种方法是，系统模态只不过是一组非常复杂的滤波器，在频率基础上具有将输入信号进行放大和衰减的能力。