In order to reduce the noise and vibration generated by rail traffic from the source, the vibration modes of the rail and the corresponding intrinsic acceleration frequency impedance amplitudes are identified from the acceleration impedance curve, by using the hammer excitation method to measure the acceleration impedance of the rail-fastener coupled system. Based on this, the most adverse irregularity wavelengths under different driving speeds are introduced by the relationship between the wavelength and excitation frequency of the irregularity. In addition, the analyses for rail frequency response, impulse response, and time-frequency of the impulse response function are done on the rail, and the dominating vibration frequencies and their vibration durations are then obtained. The dominating vibration frequencies are consistent with the results obtained from the acceleration impedance curve, and are exactly where the rail vibration and noise frequency radiation are primarily found. Thus, if the main vibration frequencies are brought under control, the full range of rail vibration and noise can be inhibited.