Use of Coherence and Frequency Response Functions to Locate and Define Vibration Noise Sources in Rolling Tires

The procedure for measuring and analyzing in-service tire vibration and sound data is described. Signal analysis techniques are applied to obtain tire vibration spectral histories, vibration-to-sound coherence, and vibration frequency response functions. Evaluation of the coherence function demonstrates the existence of a statistical relationship between tire vibration and sound. Vibration spectral histories display the decay of energy in the tire structure. Use is made of the frequency response function to determine the relative levels of vibration in the tread and sidewall regions. These results define the vibration noise source location and size.