Self-organization, and nonlinearities play crucial roles in Musical Acoustics and Music Psychology, and are formulated in modern Physical Modelling techniques and Signal Processing tools. Many musical instruments have nonlinear driving mechanisms which are crucial for producing an oscillation at all, a tight harmonic overtone spectrum, sudden phase changes, or the ability to play different tones on the instrument. Although linear theories of strings, bars, or membranes are often used to approach Musical Acoustics in general, when investigating the fundamental mechanisms nearly everywhere synchronization is the basic mode of operation.