Noun
surdo (plural surdos)
A type of percussion instrument used in Brazil.
Accompanied by a pandeiro, a tambourine, a cuíca and a surdo, they created and spread the samba-de-morro. Source: Internet
The harmony of Partido alto is always higher in pitch, usually played by a set of percussion instruments (usually surdo, pandeiro, and tambourine) and accompanied by a cavaquinho and/or a guitar. Source: Internet