This paper presents a lightweight and inexpensive infrastructure for augmented realities that uses a simple wearable computer. Whereas most traditional augmented reality systems overlay graphics onto the user's environment, this system employs only audio. Furthermore, we have created a positioning infrastructure using radio frequency (RF) transmissions that is easy to deploy, provides approximate location and uses little computational overhead. As a result, the system we created is much less expensive and computationally complex than traditional augmented reality (AR) systems. "Guided by Voices" is an AR game developed to use our prototype infrastructure that allowed us to explore the unique issues involved in creating an engaging augmented reality audio environment. We first present other systems that use personal audio in the environment followed by the infrastructure we created for our audio AR. We next describe the prototype application and describe the user's experience. Finally we present some of the issues involved in creating sound for an audio-only AR and show how our infrastructure can be generalized for use in other augmented reality systems with varying levels of user interaction.