Wailaki language

Wailaki, also known as Eel River, is an extinct Athabaskan language spoken by the people of the Round Valley Reservation of northern California, one of four languages belonging to the California Athabaskan cluster of the Pacific Coast Athabaskan languages. Dialect clusters reflect the four Wailaki-speaking peoples, the Sinkyone, Wailaki, Nongatl, and Lassik, of the Eel River confederation.

Phonology
The sounds in Wailaki:

Vowels
Vowels in Wailaki are /i e a o/, and with length as /iː eː aː oː/.