Surdo: Brazilian musical instrument

The surdo is a large drum that is used in many Brazilian music kinds. It is most notable in Axe/samba reggae and samba and its variants and there it plays the lower parts from a percussion section. The surdo sizes differ from between 16 inches to 26 inches or even 29 inches in diameter. In Rio de Janeiro surdos, they are generally about 60 cm deep. The surdos that is used in the northern part of Brazil is commonly shallower with about 50 cm deep. This musical instrument may have skin heads with aluminum shells and they can be worn from the waist belt or the shoulder strap, oriented with the head harshly horizontal. The bottom head of the instrument is not played.

source: mensageiromusical.com.br

Surdos are used by samba-reggae and axe music groups of the north-eastern part of Brazil. The samba-reggae often has two or three surdo tunings, the lowest tuning is playing the pulse on 1 and the higher tuning is always playing the 2. Middle surdos are then playing any number of counter patterns. The middle surdos can be played with two mallets in samba-reggae to give space for more complex rhythms.