Vachel Lindsay 
The Congo, and Other Poems [PDF ebook] 

Nicholas Vachel Lindsay was an American poet. He is considered a founder of modern singing poetry, as he referred to it, in which verses are meant to be sung or chanted.
His best-known poem, 'The Congo, ’ exemplified his revolutionary aesthetic of sound for sound’s sake. It imitates the pounding of the drums in the rhythms and in onomatopoeic nonsense words. At parts, the poem ceases to use conventional words when representing the chants of Congo’s indigenous people, relying just on sound alone.