Nambikwara
From Tardis Wiki, the free Doctor Who reference
The Nambikwara were a tribe from the Mato Grosso. Jo Grant lived with them for about six months in 1983. According to Jo they sang all night when there was a funeral. She thought that they sounded like birds. Jo described the sound as the most astonishing sound that she had ever heard. (TV: Death of the Doctor)
