Sound Letter is an experimental documentary that investigates the sensory identity of the city of São Paulo. Far from following a conventional linear narrative, the film proposes a kind of sonic correspondence in search of the hidden music of the metropolis. Through the perspectives of Arthur Nestrovski and Eduardo Santos Mendes, the work explores the idea that inhabiting the city means superimposing distinct times, where the contemporary noise of traffic and urban chaos coexist with echoes of centuries-old traditions, such as old street vendors' cries. The medium-length film challenges the traditional documentary form by privileging the sound element as the protagonist and openly presenting its own recording apparatus, transforming the journey of a motorcycle courier into a true ballet of forms and sounds that translate the complexity and vibrancy of the São Paulo capital.