This paper presents an acoustic study of the phonetic realization of two consonants in Nias (Indonesia), orthographically represented as mb and ndr. These consonants have been analyzed by Catford (1988) and Brown (2001, 2005) as a bilabial trill and an apical trill, respectively. My own cross-dialectal observations indicate that these consonants have multiple realizations in each dialect. This paper presents evidence for four broad phonetic realizations of both mb and ndr: most commonly a plain stop, but also a prenasalized stop, a stop with trilled release, and stop with fricated release. It seems that the variable character of the two phonemes is the only consistent feature that distinguishes them from the regular stops in the same places of articulation, and from the regular alveolar trill.
"Prenasalization and trilled release of two consonants in Nias,"
Work Papers of the Summer Institute of Linguistics, University of North Dakota Session: Vol. 50, Article 3.
Available at: https://commons.und.edu/sil-work-papers/vol50/iss1/3