In the past decades, musicology has been evolving at a pace that matches new developments in technology. Underneath this development, a new theory of music emerged, embracing interaction states as a model for understanding how music can be empowering. In the present chapter, sound design is considered from the viewpoint of interaction states, using caregiver–infant communication as a challenging domain of application. Sound design components of interest are identified, as well as human capacities for dealing with them in terms of empowerment. These are related to the concepts of self-augmented interaction and biofeedback-based sound design.