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.
Lake Tanganyika, central Africa â 1,470 meters deep (4,823 ft). It is estimated to be also the second largest freshwater lake in the world by volume. The lake is divided among four countries â Tanzania, the Democratic Republic of the Congo, Burundi, and Zambia.