Abstract: In Yue dialects in northwest Guangdong province, as a result of devoicing of unaspirated MC voiced initials, the words of MC voiced initials now are pronounced as voiceless unaspirated sounds. Since such change does not bring about much effect on its quality but shows the imbalance of Yue dialects, this feature can only be regarded as one of the criteria for sub-dividing of Yue dialects areas. In the early stage of the devoicing of voiced sounds, tones of yin and yang with significant differences are upgraded, and the role in distinguishing meanings of words is played by their tones, not the voiced initials any longer; thus, the unaspirated voiced sounds are changed into the voiceless ones. That is why MC voiced initials, which are stops or affricates, become unaspirated sounds in modern time.

Key words: Yue dialects group in northwest Guangdong, Goulou cluster, MC voiced initials, unaspirated voiced, unaspirated voiceless, devoicing