Squeal noise is observed frequently when one metal counter face slides over another metal counter face under certain conditions. Squeal frequency range is 500 Hz - 20 kHz, with very sharp peaks and high sound pressure level. Two cases that squeal noise is often found are railway systems and braking systems. In this book author proposes new experiment-based method to predict squeal noise occurrence in a structure with friction. It is found that modal coupling instability analysis is an appropriate mechanism to explore more deeply about this kind of noise. There are two aspects that...