The most convincing explanation is that when someone is finding it difficult to understand what is said to them, he/she engages in a form of lip-reading: he/she will observe the lips of the talker and mimic the talker's lip movements.
Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, in both cases, after only Lake Baikal in Siberia; it is also the world's longest freshwater lake.
The largest lake by area on the African continent is Lake Victoria, which borders the countries of Uganda, Kenya, and Tanzania.he largest lake in Africa is Lake Victoria, which is the  second-largest lake in the world. The second largest lake in Africa  is Lake Tanganyika.