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Bongo also has vowel harmony. The "heavy" vowels, written with diaereses, (/i/, /u/, /e/, /o/, /ə/) contrast with the "light" vowels (/ɪ/, /ʊ/, /ɛ/, /ɔ/, /a/).
Tone
Bongo is tonal language that has the high (á), mid (ā), low (à) and falling (â) tones.
All falling tones occur on either long vowels or on vowel clusters or glides. When the tonal fall is not due to a preceding high tone, it can be indicated by a high tone followed by a low tone.
The first ethnologists to work with the Bongo language were John Petherick, who published Bongo word lists in his 1861 work, Egypt, the Soudan, and Central Africa; Theodor von Heuglin, who also published Bongo word lists in Reise in das Gebiet des Weissen Nil, &c. 1862-1864 in 1869; and Georg August Schweinfurth, who contributed sentences and vocabularies in his Linguistische Ergebnisse, Einer Reise Nach Centralafrika in 1873. E. E. Evans-Pritchard published additional Bongo word lists in 1937.
More recent scholarship has been done by Eileen Kilpatrick, who published a phonology of Bongo in 1985.
Evans-Pritchard, E. E. (1929). "The Bongo". Sudan Notes and Records. pp. 1–62.
Evans-Pritchard, E. E. (1937). "The non-Dinka peoples of the Amadi and Rumbek Districts". Sudan Notes and Records. pp. 156–158.
Kilpatrick, Eileen (1985). "Bongo Phonology". Occasional Papers in the Study of Sudanese Languages. 4: 1–62.
Further reading
Crystal, Kathryn; Armand, Matthew; Armand, Breanna (2020). Sociolinguistic Survey of the Bongo of South Sudan (Report). SIL Electronic Survey Reports. Vol. 2020–010. Dallas: SIL International.
Moi, Daniel Rabbi; Kuduku, Mario Lau Babur; Michael, Sister Mary Mangira; John, Simon Hagimir; Mafoi, Rapheal Zakenia Paul; Kuduku, Nyoul Gulluma (2018a). Bongo Grammar Book (PDF) (3rd trial ed.). Juba: SIL-South Sudan.
Moi, Daniel Rabbi; Kuduku, Mario Lau Babur; Michael, Sister Mary Mangira; John, Simon Hagimir; Mafoi, Rapheal Zakenia Paul; Kuduku, Nyoul Gulluma (2018b). Bongo Consonant and Vowel Book (PDF). Archived from the original (PDF) on 2024-02-18.
Santandrea, Stefano (1963). A Small Comparative Vocabulary of Bongo Baka Yulu Kara. Rome: Sodality of St Peter Claver.
Thayer, Linda Jean (1974). A Reconstructed History of the Chari Languages: Comparative Bongo-Bagirmi-Sara Segmental Phonology With Evidence From Arabic Loanwords (PhD thesis). University of Illinois at Urbana-Champaign. hdl:2142/63560.