So I know for certain words, such as 不对, the fourth tone changes, but I believe 不 may be a special case.

Some words such as 部队 seem uncomfortable to pronounce if I strictly follow 4th and 4th tones, but saying words such as 汉字, don't feel as uncomfortable.

Is there a general rule (or at least a general rule with a few exceptions), for pronouncing double fourth tone words?

  • Nothing wrong with double 4th tones; they're indeed pronounced that way. 不 is one of the few special cases where tone-sandhi is applied. In every language there might be pronunciations that feels strange or uncomfortable to language learners.
    – NS.X.
    Commented Sep 25, 2015 at 18:14

3 Answers 3


Yes, 不 is a special case. Other consecutive fourth tone morphemes are all pronounced (事件, 现在, 俱乐部), unless the word formed itself is a special case where the tone of the last morpheme is neutralized (看见, 用处, 味道).


Yes, they do feel uncomfortable to pronounce, but they are indeed pronounced two 4th tones.

Except the 不 case, in which it changes to 2nd + 4th.


There is a general rule for tone 4, but it concerns sequences of length three rather than consecutive fourth tones. The rule is as follows:

For conversational speech, tone 4 becomes lower and flatter, but still slightly falling, akin to Cantonese tone 3, when put between tone 3 or 4 and tone 1 or 4.

Something similar occurs for tone 2: it becomes higher and changes its direction, approaching the tone 1 pitch contour, when put between tone 1 or 2 and any other full tone.

I give a bit more detail on this in a different answer.

This "sandhi" rule/phenomenon does not seem to be very well known among students and teachers of Chinese. I only learnt about it when looking at the Wikipedia reference.

Reference: wikipedia

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