Guided by Voices explores a different design space than previous audio augmented realities. Bederson [2] describes a related nonlinear sound playback system triggered by location using infrared beacons. The sounds presented provide detail on real life artifacts the user observes. Our system extends this concept to utilize state information on a wearable device to play different sounds for different situations at the same location.
Nomadic Radio [5] utilizes sound to inform the user of incoming messages and events. It further permits the user to control the audio's intrusiveness level. Audio Aura [4] explores several different soundscapes for displaying ambient information. Both systems provide a hint of the information content and significance through ambient sounds. They try not to burden the user or deflect the user's attention away from his/her current task unnecessarily while presenting information. In contrast, Guided by Voices explicitly engages the user in the audio environment through narration, sound effects and ambient audio. It exploits player location and history to play contextually appropriate sounds and uses lightweight and inexpensive wearable computers that require minimal explicit user input.
Figure: Left - The inside of the wearable device showing
the Diamond Rio 
, the RF receiver, the PIC
microcontroller and a 9V battery. The inset is the closed unit. Right - The RF
transmitter attached to a 9V battery.