Mark Aitken examines the relationship between photography and sound. This week: In photography, the past is always present. Brazilian artist André Penteado discusses his series of books Traces, trails and remains, about Brazilian history and how past events seep into present meaning and even events themselves. In particular, the Cabanagem revolt now being reflected in current protest and violence in the largest and most abundant country in South America. With music by Caetano Veloso, Coil and Popul Vuh.