With our Ubiquitous Sonic Overlay, we are working to place virtual sounds in the user's environment, fixing them in space even as the user moves. We are working toward creating a seamless auditory display, indistinguishable from the user's actual surroundings. Between bone-conduction headphones, small and cheap orientation sensors, and ubiquitous GPS, a confluence of fundamental technologies is in place. However, existing head-tracking systems either limit the motion space to a small area (e.g., Oculus Rift), or sacrifice precision for scale using technologies like GPS. We are seeking to bridge the gap to create large outdoor spaces of sonic objects.