On Ibo Island, in northern Mozambique, a woman pounds using a pestle, tossing it into the air and marking the rhythm with a clap in between. The tempo adjusts moment by moment—starting off briskly, then slowing as her body tires. After a short rest, she resumes, lifting the pestle again into the air and marking the same beat with a mid-motion clap.

Ibo island. 1996 © Jorge Murteira. All rights reserved.

Ibo island. 1996 © Jorge Murteira. All rights reserved.

The sound was recorded by Francisco Leal in August 1996. It was captured for the Cultures of the Indian Ocean exhibition, promoted by the Portuguese National Commission for the Commemoration of the Discoveries, which opened in May 1998 at the National Museum of Ancient Art.

Ibo island. 1996 © Jorge Murteira. All rights reserved.

Ibo island. 1996 © Jorge Murteira. All rights reserved..