This article gathers some reflections on how the graphical representations of sound and the graphical interfaces can help making and controlling digital audio effects. Time-frequency visual representations can help understand digital audio effects but are also a tool in themselves for these sound transformations. The basic laws for analysistransformations-resynthesis will be recalled. Graphical interfaces help for the control of effects. The choice of a relation between user control parameters and the effective values for the effect show the importance of the mapping and the graphical design. Graphical and sonic editor programs have both in common the use of plug-ins, which use the same kind of interface and deal with the same kind of approach.