Nyaheun (also known as Nhaheun, Yaheun, Nyahon; autonym: Heun [hɐɐɲ]) is a Mon–Khmer language of the Bahnaric branch spoken in southern Laos. Chazée (1999:95) estimates the population at 4,200, while the 1995 Laotian census places the Nyaheun population at 5,152.
Nyaheun speakers were formerly distributed in the Senamnoy and Sepian balleys, but due to logging and hydroelectric power projects, they were forcibly relocated to Ban Tayeukseua (Tagneugsua; about 10 km southwest of Houeikong), and a new village 8 km north of Houeikong (near Ban Thongvay) (Sidwell 2003:21).
- Sidwell, Paul (2003). A Handbook of comparative Bahnaric, Vol. 1: West Bahnaric. Pacific Linguistics, 551. Canberra: Research School of Pacific and Asian Studies, Australian National University.