In the urban landscape it can be hard to distinguish a sign from a trace and sometimes even from a piece of garbage. The global popularity of shoe tossing, the practice of throwing worn out shoes over telephone wires, can be partially attributed to this ambiguity. What does it mean when a pair of shoes are seen hanging overhead? While the motives of shoe-tossers remain unknown, they have inspired a new activity which has an official explanation and even a founder. Sound Tossing is a practice initiated by artist-activist Soundfiti as a sonic form of street art. Having originated in Linz it is spreading to many locations across the globe, including Mumbai, Istanbul and London. Sound Tossing involves throwing a small sound-emitting device over telephone wires, power lines or other protruding urban structures to mark a location with a sound. Emerging after LED throwies and laser graffiti in the field of new media street art, sound tossers are appropriating the city landscape by inserting their own sonic signatures. Following a simple online tutorial anyone equipped with a soldering iron can assemble a few electronic components to produce a small self-contained device powered by solar energy. The basic version of the device emits a regular cricket-like sound, but by changing a few bits and pieces, it’s easy to personalize the unit. More complex variations include a miniature pirate radio station, transmitting over a range of a few meters, as well as a throwable electromagnetic sniffer (a device for revealing electromagnetic fields). Refraining from the temptations of sonic dominance, the low power of these objects ensures their discreetness. Like small insects, rather then adding to the clutter of the urban soundscape, they insert a missing layer of detail, encouraging passers-by to listen more carefully to their surroundings.