Loudspeakers are more than just technical devices. They change the way we listen to sound and music and can become instruments or performers themselves. Portable sound sources such as the boombox and the Walkman inspire new forms of sound art because they invite us to listen while walking. In her essay, Margarethe Maierhofer-Lischka describes how "listening in transition" can be shaped and why she finds loudspeakers so fascinating as a material.