Reconstructions have been proposed by Malcolm Ross and Andrew Pawley.
Proto-Trans–New Guinea is reconstructed with a typical simple Papuan inventory: five vowels, /i e a o u/, three phonations of stops at three places, /p t k, b d ɡ, m n ŋ/ (Andrew Pawley reconstructs the voiced series as prenasalized /mb nd ŋɡ/), plus a palatal affricate /dʒ ~ ndʒ/, the fricative /s/, and the approximants /l j w/.
The Proto-Trans–New Guinea vowels are reconstructed as having a cross-linguistically frequent five-vowel system: Ross reconstructs the following pronominal paradigm for Trans–New Guinea, with *a~*i ablaut for singular~non-singular: There is a related but less commonly attested form for 'we', *nu, as well as a *ja for 'you', which Ross speculates may have been a polite form.
(Reflexes of the collective suffixes, however, are limited geographically to the central and eastern highlands, and so might not be as old as proto-Trans–New Guinea.)
Studies group Madang, Finisterre-Huon, and Kainantu-Goroka together as part of a larger Northeast New Guinea (NENG) group on the basis of morphological evidence, such as mutually reconstructable verbal suffixes that mark subject:[2][1]: 147–148 Lexical words, such as *niman 'louse', may also be reconstructed: The Proto-Trans–New Guinea negative is reconstructed as *ma-.