Voicing or register in Jarai dialects? Implications for the reconstruction of Proto-Chamic and for registrogenesis

Jarai is a Chamic language of Vietnam and Cambodia that is traditionally described as preserving the original Austronesian voicing contrast in onset obstruents. However, there is anecdotal evidence that it has developed a register contrast, i.e. a binary contrast based on a bundle of spectral properties like pitch, voice quality and vowel quality. We conducted production and perception experiments of the voicing/register contrast in two Jarai varieties spoken in Saom Kaning, Cambodia, and Ea Sup, Vietnam, to determine if they preserve voicing and/or have developed a register contrast. Results show that both dialects have a register contrast primarily based on vowel height modulations (F1) and that onset voicing has become at best an optional secondary property of register. F1 is also the primary cue used for register identification in both dialects. Implications for the diachronic development of the register contrast in Chamic languages and in Mainland Southeast Asia in general are discussed.