We went in search of the world’s hardest language
For sound complexity, one language stands out. !Xóõ, spoken by just a few thousand, mostly in Botswana, has a blistering array of unusual sounds. Its vowels include plain, pharyngealised, strident and breathy, and they carry four tones. It has five basic clicks and 17 accompanying ones. The leading expert on the !Xóõ, Tony Traill, developed a lump on his larynx from learning to make their sounds. Further research showed that adult !Xóõ-speakers had the same lump (children had not developed it yet).
Tuyuca, of the eastern Amazon has a sound system with simple consonants and a few nasal vowels, so is not as hard to speak as Ubykh or !Xóõ. Like Turkish, it is heavily agglutinating, so that one word, hóabãsiriga means “I do not know how to write.” Like Kwaio, it has two words for “we”, inclusive and exclusive. The noun classes (genders) in Tuyuca’s language family (including close relatives) have been estimated at between 50 and 140. Some are rare, such as “bark that does not cling closely to a tree”, which can be extended to things such as baggy trousers, or wet plywood that has begun to peel apart.
Most fascinating is a feature that would make any journalist tremble. Tuyuca requires verb-endings on statements to show how the speaker knows something. Diga ape-wi means that “the boy played soccer (I know because I saw him)”, while diga ape-hiyi means “the boy played soccer (I assume)”. English can provide such information, but for Tuyuca that is an obligatory ending on the verb. Evidential languages force speakers to think hard about how they learned what they say they know.
via https://medium.com/the-economist/we-went-in-search-of-the-worlds-hardest-language–95a27c2cff3