Brazilian bass drum; referred to as the heart beat of the samba. The Bahia-style drum is of shallower construction than a Rio-style surdo. The head diameter is generally greater than the depth of the shell.

( soor du) is a Brazilian double headed bass drum carried in parades and played with a mallet and one hand, or two mallets. Surdos come in various sizes including 14 X 20 , 16 X 20 , 20 X 20 20 X 24 and 24 X 24. Surdos are made with a metal or thin wood shell and originally had goat skin heads. Plastic heads are common now and many groups from Bahia now put a layer of naugahide or split cowhide over the plastic, producing a more low end sound.

The Surdo is a large bass drum used in many kinds of Brazilian music, most notably samba.