In a modern urban setting, the organization of architectural space structures spatial proximity in the same fashion as peculiarities of natural landscape defined it for our nomadic primogenitors. Patterns of face-to-face interactions in a building are, to a large extent, defined when architects differentiate spaces in it for distinct functions and organize circulation between the spaces. Buildings of the future could be instrumented to inform communication devices carried by their inhabitants and visitors about the intercommunication configuration of spaces within and outside them, thus defining proximity in software. The goal of this project is to develop and evaluate a prototype wearable system for proximity-based synchronous voice messaging in a space configured for intercommunication. Potential applications range from wearable computers promoting ad hoc collaboration within organizations to communication systems for firefighters.