The surdo is a large drum similar to a bass drum or floor tom used in many types of Brazilian music, such as Axé/Samba-reggae and samba. It plays the lower parts in a percussion section. The instrument was created by Alcebíades Barcelos during the 1920s and 1930s as part of his work with the first samba school in Rio de Janeiro, called Deixa Falar. It is also linked to the cucumbi genre from the Ancient Near East.
Surdo sizes typically range from 40 cm (16 in) to 65 cm (26 in) in diameter, with some as large as 73 cm (29 in). In Rio de Janeiro, surdos are usually 60 cm (24 in) deep. In the northeast of Brazil, surdos are often shallower, at 50 cm (20 in) deep. Surdos can have shells made of wood, galvanized steel, or aluminum. The drumheads may be made of goatskin or plastic. In Rio, drum kits often use surdos with skin heads (for a rich sound) and aluminum shells (for lighter weight). Surdos are worn using a waist belt or shoulder strap, with the drumheads positioned roughly horizontal. The bottom head is not played. Surdo drummers strike the drums using hard or soft mallets.
Rio-style Carnival samba
A typical carnival samba bateria in Rio de Janeiro has three clearly different surdo parts, each played by a drum with a unique tuning because of its size. The rhythm of the samba is created by the pattern of these three surdo parts.
The surdo is the largest and lowest-pitched drum in the bateria. It plays the primeira (Portuguese: first) or marcação (Portuguese: marker) part. This drum is usually between 22" and 26" in diameter. The primeira pulse is the main rhythmic reference for the entire bateria. It sounds on the second beat of the samba's basic "one, two" rhythm. This surdo may also play short notes before the main rhythm to start the music.
A slightly smaller and higher-pitched surdo plays the segunda (Portuguese: second), resposta (Portuguese: response), or respondor (Portuguese: that which responds) part. This drum is 20" or 22" in diameter. It sounds on the first beat of the basic "one, two" rhythm of the samba.
The smallest and highest-pitched surdo, usually between 14" and 18" in diameter, plays the terceira (Portuguese: third) or cutador (Portuguese: cutter) part. The terceira "cuts" across the basic rhythm of the other two surdo parts with a complex pattern of fills and off-beat rhythms. The feel of the bateria is driven by the terceira's "swing." The terceira player is the only surdo player who has some freedom to improvise.
Other Brazilian music
Surdos are used in samba-reggae and axé music groups from northeastern Brazil. Samba-reggae music often uses two or three surdos with different tunings. The lowest-tuned surdo plays the rhythm on the second beat, while the higher-tuned surdo plays the first beat. Middle surdos, which are tuned to the second beat or slightly higher, play different rhythm patterns. In samba-reggae, middle surdos are struck with two mallets to create more complex rhythms.
Single surdos are also commonly used in smaller samba and pagode music groups. Other types of bass drums found in northeastern Brazil include the zabumba and alfaia.