If trees had ears? In this preliminary study for The Social Lives of Urban Trees we brought an accelerometer, a hydrophone, an ultrasonic microphone, and various special purpose transducers to audition a London planetree (Platanus x acerifolia) planted at a city streetcorner. The ears of humans and many animals use air as the vector for sound transmission. Trees are said to be more receptive to earthborne vibrations, which they sense through their roots. Although we can only speculate what a tree might hear, our intention was figuring out how to listen to the tree’s presence among its urban milieu.