Our central theme is ubiquity and complexity in digital media culture. So you can see why we were so interested in having you participate in the project. I am particularly interested in your work because of your long experience with sound and sound-based installations. 1 Sound has been a neglected feature in mainstream work on augmented reality (AR) by computer scientists. But as AR and mixed reality (MR) are beginning to be applied on a large scale, which is now possible because of smart phones, sound is becoming an increasingly important feature. Your work is central for that reason, among many others. In discussing your work, we could begin with Trace, which I understand was your first GPS-based sound walk?