I’m watching Louis Gates in Brazil, and he’s visiting a capoeira master. There are men marking cadence with an unusual instrument. It’s a bowed rod with a single string and a resonator, and the string is tapped with a drumstick. What is this called?
As Twoflower already answered the question posed by the OP I’ll just link to a couple of curiosities: first is Flora Purim’s rendition of Cravo e Canela. At 2:30 her husband, Airto Moreira, begins playing a *berimbau *solo that has to be heard to be believed. Second, for guitar fans, Baden Powell wrote a song called Berimbau in which he he emulates that instrument’s sound on his guitar and which was the starting point of his and Vinicius de Moraes’ Afro Sambas (all of which are amazing and were hugely influential here in Brazil, even though the album is hard to find nowadays; even in youtube I had no luck searching for the originals).