Trąbizupka – Warsaw’s mobile field kitchen – was a charitable initiative of the early years of the 20th century; a cart going around Warsaw sold nutritious and cheap soup, and its arrival was accompanied by the sound of a trumpet. This peculiar sound phenomenon existed in the city’s phonosphere for a short time – the residents had to learn to interpret it, but after a few years, trąbizupka’s activity was suspended. The functioning of trąbizupka (manifested through its sonicity – literally, in the sound of the trumpet, and figuratively, in the name itself) was coupled with a class discourse on charity – from admiration for the initiative to the feeling of shame of Warsaw’s folk classes, as reported “first-hand” by the positivist “Przegląd Tygodniowy” [Weekly Review], linked to eating a pauper’s meal “on the street.” At the same time, trąbizupka became an element of urban folklore, preserved in popular polkas for piano and as a sound characteristic of Warsaw. Trąbizupka, as a case study analyzed from the position of historical sound studies, allows us to ask questions about the sound signal as a vehicle of communication and about the acoustemology of the city’s residents, especially of the lower social classes, at the turn of the 20th century. Key-words: acoustemology, audiosphere, sound history, sound studies, Warsaw