The guitar can be described in terms of impulse patterns. Here we view the guitar as consisting of five subsystems, the string, top plate, back plate, ribs, and inclosed air. All of them are interacting and driven by impulses. The string is "knocking" on the top plate periodically. If the string is displaced in a trapezoid manner and then set free, the trapezoid motion is travelling cyclically around the string. At the bridge point the changing angle of the string and its higher derivatives cause a force on the top plate. The time dependence of this force is an impulse train in the periodicity of the fundamental frequency of the string.