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In the Sakon Nakhon languages, Proto-Tai *hw- and *w- (Pittayaporn 2009:134-135) became /ph/- (Trongdee 2016:55). Also, the Sakon Nakhon languages display the uncommon labiovelar initial clusters thw-, cw-, sw-, hw-, ŋw-, lw-, ʔw- (Trongdee 2016:56).
Internal classification
Thananan Trongdee classifies the Kaloeng dialects as follows according to the evolution of the Proto-Kaloeng diphthong *-aɯ.