The Yong'an dialect has extremely extensive tone sandhi rules: in an utterance, only the last syllable pronounced is not affected by the rules. The two-syllable tonal sandhi rules are shown in the table below:
Tone sandhi of first syllable
Original citation tone
Tone sandhi
upper level
lower level
lower level
remain unchanged
upper rising
lower level
lower rising
upper rising
departing
remain unchanged
entering
high level (55)
Notes
^Min is believed to have split from Old Chinese, rather than Middle Chinese like other varieties of Chinese.[1][2][3]
References
^Mei, Tsu-lin (1970), "Tones and prosody in Middle Chinese and the origin of the rising tone", Harvard Journal of Asiatic Studies, 30: 86–110, doi:10.2307/2718766, JSTOR2718766