Just as a doctor may take your pulse to test your response to stress, an engineer can take the pulse of a structure to see how it's doing. The engineer uses modal analysis. This method of testing shows how large complex structures such as high-rise buildings respond to induced or ambient vibrations such as traffic or wind. Dynamic response shapes appear on a computer screen showing a structure's fingerprint. Later changes in this fingerprint may signal damage. Modal analysis goes beyond standard measurements or inspections; it shows the actual performance of a structure under real conditions.