Cardiff's introduction to the Audio Walks sums it up perfectly:
The format of the audio walks is similar to that of an audioguide. You are given a CD player or Ipod and told to stand or sit in a particular spot and press play. On the CD you hear my voice giving directions, like “turn left here” or “go through this gateway”, layered on a background of sounds: the sound of my footsteps, traffic, birds, and miscellaneous sound effects that have been pre-recorded on the same site as they are being heard. This is the important part of the recording. The virtual recorded soundscape has to mimic the real physical one in order to create a new world as a seamless combination of the two. My voice gives directions but also relates thoughts and narrative elements, which instills in the listener a desire to continue and finish the walk.
I found that this was such a great idea and method for storytelling that combines the aural pleasure and effect of listening to a soundscape while moving through a space which corresponds to the audio. After hearing Her Long Black Hair (2004), I loved this idea of dislocation between time and space, the relationship between the physicality of a space and our perception of imaginary space through audio. I'll have to do a bit more research on this form of locative media and mapping to find out if there was something similar in Sydney. It would definitely be worth looking out for and experiencing.