Urban Sonar is a personal space monitoring system that senses an individual's experience as they move through the urban environment and records that information for review at a later time. Turning the gaze both outward and inward, negative space surrounding the individual and their heart rate are used to visualize a lived experience through quantitative data.

The sensing system is integrated into a wearable device. Ultrasonic range finders are mounted in the front, back, and shoulders of a jacket, measuring the empty space or proximity to solid forms on all sides of the body. Conductive fabric strips are strapped around the fingers and serve as the contact leads for a heart rate monitor that registers pulse. The remaining electronic components are housed in a pocket inside the jacket. Sensor data is fed into a microcontroller that interprets the values and transmits them serially via Bluetooth. The data is received and recorded by a Bluetooth-enabled mobile phone. Once the session is complete, the log file is uploaded from the mobile phone to a server where it is interpreted as a time-based visualization. This visualization displays an accelerated, aerial view that simulates the ebb and flow of the user's personal space and heart rate as the values fluctuate during the period of data logging.

Considering both the body and its movement through space, Urban Sonar is a mobile, wearable, logging system that uses objective data to map a subjective experience.