Abstract: A multi-sine vibration testing method includes coupling a vibratory excitation source and a sensor to a test structure, then providing a reference signal to the excitation source, wherein the reference signal comprises a first sinusoidal waveform having a first frequency and a second sinusoidal waveform having a second frequency different from the first frequency. The first frequency and the second frequency each sweep between a corresponding start value and a corresponding end value, and the frequency response is measured from each of the sensors while providing the reference signal.