What is a surdo in music?

In music, a surdo is a large, single-headed frame drum commonly used in Brazilian samba music. It is traditionally played with the hands and produces a deep, resonant sound. Surdos come in various sizes, with the largest ones known as surdos de primeira or surdos de terceira. They are typically played in a bateria (drum ensemble) alongside other percussion instruments such as cuícas, caixas, tamborims and agogôs, creating the characteristic rhythm of samba music.