The visual arts and music have often been considered as separate modes of cultural expression or as activities in which one of them predominates thoroughly and appeals entirely or almost entirely to either the sense of sight or to the sense of hearing. Threshold is a concept closely related to the event-ness of performance. This chapter explores how both the presence and the absence of voice in its sung and spoken forms are the thresholds that allow a conjuring up of multiple and mirroring subjectivities, viewpoints and the fragility of their borders. It explores how an artistic form's ability to transgress its own borders allows the migration from vision to sound and vice versa, in ways that may question the identity of the original form. The chapter explores how thinking about synchronization and synchresis illuminates the relationships between sound and image beyond the realm of sound cinema for which they are frequently reserved.