William “Bilwa” Costa’s work straddles the boundaries of sound action, composition, site-relative installation and performance or controlled choreography. The format of his artistic output often combines several of the aforementioned positions without the result appearing too complicated. He reduces the artistic means he uses in his works either through a certain “aesthetic purification” or through the use of simple and accessible devices, technologies and media. Participants in his public intervention entitled dialogue [1–9], which took place at the opening of the festival, used only the recorder on their smartphones and their own voice in the performance. Their task was to form pairs and take turns recording themselves in any situation while counting aloud from one to nine. Each recording of one participant counting then formed the basis of the other participant counting during the event. The resulting recordings, with multiple layers of recorded voices, were then played simultaneously by all the participants, creating a kind of chorus reproduced in unison in the crowd attending the opening. The process of repeated recording of replayed recordings is a long-established principle of sound experimentation that brings into play the tone of voice, the acoustics of the environment with its natural and accidental sounds, as well as the properties of the medium on which the recording is made and through which it is reproduced. However, its application in a specific context, where the event itself becomes part of public space, the use of means that allow direct public participation and the limits of the content move the event closer to the form of an ephemeral monument to the age of mediated communication.