A word-final /k/ can also be heard as a glottal stop [ʔ].
Vowels
Vowels /i, u, e, o/ can have shortened allophones of [ɪ, ʊ, ɛ, ɔ].[2]
References
^Pakpak at Ethnologue (18th ed., 2015) (subscription required)
^Simbolon, Apul; Tinambunan, Raman; Pardede, Bertha (1978). Fonologi bahasa Batak Dairi. Medan: Proyek Penelitian Institut Keguruan dan Ilmu Pendidikan.
Further reading
Sembiring, Matius C.A.; Aiyub, T.; Amillah, R.; Perangin-angin, P. (1993). Morfologi dan Sintaksis Bahasa Pakpak Dairi [Morphology and Syntax of the Pakpak Dairi Language] (in Indonesian). Jakarta: Pusat Pembinaan dan Pengembangan Bahasa, Departemen Pendidikan dan Kebudayaan. ISBN 979-459-293-5 – via repositori.kemdikbud.go.id.
Basaria, Ida (2002). Analisis Morfologi Verba Bahasa Pakpak Dairi [Morphological Analysis of Pakpak Dairi Language Verbs] (Thesis) (in Indonesian). Universitas Sumatera Utara.
Kudadiri, Amhar (2010). Morfologi Nomina Bahasa Pakpak [Noun Morphology of the Pakpak Language] (Thesis) (in Indonesian). Universitas Sumatera Utara.
Brakel-Papenhuijzen, Clara (2014). Dairi Stories and Pakpak Storytelling. Leiden, The Netherlands: Brill. doi:10.1163/9789004261730.
Pangaribuan, Mintauli (2017). Analisis Morfologi Verba Transitif Bahasa Pakpak Dairi [Morphological Analysis of Transitive Verbs in the Pakpak Dairi Language] (Thesis) (in Indonesian). Universitas Sumatera Utara.
Pakpak language test of Wikipedia at Wikimedia Incubator