This podcast episode explores the cultural significance of sound in Mexico, from the iconic scrap metal collection call "Fierro Viejo" to the unique intonations and phrases used by street vendors to attract customers. It delves into the backstory of Fierro Viejo, a father-daughter duo's pregon that transformed into a national sensation, and the challenges faced by the scrap metal crews in the informal economy of Mexico City. The episode also examines the work of Felix Blum, a French sound engineer dedicated to recording and archiving the sounds of street vendors, highlighting the importance of public spaces as platforms for expression and communication.