What Is Tone Sandhi?

What does tone sandhi mean?

Tone sandhi is a change in the tone of a syllable when that syllable is pronounced together with other syllables. A word may have one tone when said on its own but a different tone when it appears in a word or phrase. The change follows patterns that speakers learn as part of their language’s sound system.^[1]

The best-known example comes from Mandarin Chinese. The greeting 你好 is normally written in pinyin as nǐ hǎo. Both syllables have the third tone in their dictionary forms. In ordinary connected speech, however, the first syllable takes a rising tone, so the greeting is pronounced approximately ní hǎo.^[3]

The meaning has not changed, and the characters are still the same. What changes is the pronunciation of the first syllable because of the tone that comes after it. The word sandhi comes from Sanskrit and refers to a joining or connection, a useful description for changes that occur when sounds or words meet.^[1]

First, what is a lexical tone?

In a tone language, differences in pitch can distinguish one word or grammatical form from another. Linguists call a meaning-distinguishing tone a lexical tone. Pitch is the perceived highness or lowness of a voice; a tone is a language-specific pattern that uses pitch, often together with other phonetic cues, to make a linguistic distinction.^[2]

Standard Mandarin has four main lexical tones, as well as a neutral-tone category. Using the syllable ma, the four main tones are often introduced like this:

These descriptions are useful starting points, not exact pitch shapes for every speaking situation. In particular, Mandarin’s third tone often sounds mostly low in connected speech, rather than displaying a complete fall and rise. Tone sandhi is one important reason the tone you hear may differ from the simplified shape shown in a beginner’s chart.^[4]

How third-tone sandhi works in Mandarin

The familiar Mandarin rule is straightforward: within the relevant phrase, a third tone becomes a second tone before another third tone. Linguists can represent it as T3 → T2 / __ T3, meaning that T3 changes to T2 when another T3 follows it.^[5]

The following examples show the usual dictionary tones and the resulting connected pronunciation. The highlighted syllable is the one whose tone changes.

Does every third tone make a full dip?

No. Before a first, second, or fourth tone, Mandarin’s third tone is generally realized as a low tone, often called a half-third tone. It commonly lacks the final rise heard in a careful, isolated pronunciation. This is a different observation from the T3-to-T2 change before another third tone: one involves the usual contextual shape of T3, while the other is conventionally described as a categorical tone-sandhi rule.^[4]

What happens with three or more third tones?

When several third-tone syllables occur in a row, the rule is not always applied as though every pair belonged to one undivided string. The results can depend on how speakers group the syllables into words and prosodic units. A three-syllable sequence may be divided into a one-syllable plus two-syllable group, or into a two-syllable plus one-syllable group, and that grouping can affect the tone pattern.^[6]

This is why textbooks often introduce two-syllable third-tone sandhi first. The simple T3 + T3 rule is reliable and useful, but longer sentences show that tone sandhi is connected to prosody, the organization of speech into rhythmic and intonational groups. Word boundaries, phrasing, and speaking style can all be relevant; a pause may separate syllables that would otherwise interact.^[6]

Tone changes in 一 (yī) and 不 (bù)

Mandarin also has familiar, highly regular tone changes involving two common words: 一 (yī, “one”) and 不 (bù, “not”). Their pronunciation depends on the tone of the following syllable, although each word has its own pattern.^[3]

The tone of 一 (yī)

When yī is used before another syllable in many ordinary expressions, it becomes yí before a fourth tone and yì before a first, second, or third tone. It generally stays yī when used in counting and some numerical or ordinal expressions. Certain repeated-verb constructions use a neutral-tone yi instead.^[3]

The tone of 不 (bù)

Bù normally has a fourth tone. Before another fourth-tone syllable, it becomes bú. Before first-, second-, or third-tone syllables, it generally keeps its fourth tone. Some unstressed constructions have a neutral-tone form as well.^[3]

These words are useful reminders that tone sandhi does not name just one rule. Different tones and different lexical items can have different conditions for alternation.

Does tone sandhi work the same way in every language?

No. Tone sandhi is particularly well documented in varieties of Chinese, but the processes differ substantially. Some are mainly triggered by adjacent tones; others depend strongly on where a syllable occurs in a word or phrase. Similar tonal alternations are also discussed for languages beyond the Chinese family, although researchers do not always use the term tone sandhi in exactly the same way.^[1]

Taiwanese Southern Min: position matters

In Taiwanese Southern Min, also called Taiwanese Hokkien, tones commonly change on non-final syllables within a tone-sandhi group. The final syllable generally retains a citation or phrase-final tone, while preceding syllables take forms determined by an organized system of tonal alternations. Several of these alternations form chains often described as a tone sandhi circle.^[7]

This diagram shows the positional tendency, not a complete tone chart. Which tone replaces which depends on the type of syllable and the variety being spoken. In descriptions of Taiwan Min, for example, a non-final low-falling tone conventionally written 31 can surface with a high-falling contour 51. The numbers refer to relative pitch levels, not to the numbered Mandarin tone categories.^[7]

Shanghai Wu: the first syllable can dominate

Shanghai Wu provides another contrast. In a common compound-tone pattern, the tone associated with the first syllable shapes the pitch pattern across the larger word. Linguists call this left-dominant tone sandhi. It is not the same as Mandarin’s familiar rule of turning the first of two third tones into a second tone.^[8]

These examples show that the term covers several related phonological systems rather than one universal formula. The triggers, the affected syllables, and the boundaries of the changes have to be learned for each language or variety.

How is tone sandhi different from other pitch changes?

Pitch never stays perfectly constant in connected speech. A preceding tone can influence the pitch at the beginning of the next syllable, and a speaker can raise the pitch of an entire sentence to express emphasis or a question. These are not necessarily the same kind of change as a language’s tone-sandhi rule.^[9]

Researchers distinguish these processes using more than a listener’s impression. They examine pitch measurements, whether a change is predictable from a phonological category or merely graded, and whether listeners treat two pronunciations as forms of the same underlying tone. The boundary is not always simple: even after Mandarin third-tone sandhi, careful acoustic studies sometimes find small differences between a sandhi-derived rising tone and an ordinary lexical second tone.^[5][9]

Is tone sandhi shown in writing?

Not always. Chinese characters generally do not record tones directly. Pinyin dictionaries and word lists often preserve the citation tone, the tone associated with a syllable when the word is given on its own, while teaching materials sometimes write the changed pronunciation to help learners speak naturally. This is why you may see nǐ hǎo in a vocabulary list and be taught to say ní hǎo.^[3]

It helps to keep two forms in mind: the underlying or citation form and the form used in a particular spoken context. The exact conventions for transcribing sandhi depend on the language, romanization system, and purpose of the material.

Why tone sandhi matters for pronunciation and listening

A learner who memorizes only isolated dictionary tones may still find connected speech difficult to follow. The syllables are familiar, but their pitch patterns can change once they are spoken together. Learning the sandhi rules helps explain why a familiar expression does not always sound like its written tone marks.

For Mandarin, a practical approach is to start with two adjacent third tones, then learn the usual changes of yī and bù. Listen to complete phrases rather than practicing every syllable in isolation. Longer strings should be learned with attention to how a native speaker groups the words, rather than by applying a rule mechanically across every possible boundary.

Tone sandhi also matters to linguistic research. Experiments show that listeners use prosodic structure when interpreting pronunciations affected by Mandarin third-tone sandhi. Research on how children acquire tone alternations and how adults produce them helps explain the relationship between the sounds stored for words and the sounds actually heard in speech.^[6][10]

Sources

• [1]Chen, Matthew Y. Tone Sandhi: Patterns across Chinese Dialects. Cambridge University Press, 2000. Read the sourceDefinition, the term sandhi, and the range of tonal alternations
• [2]Lee, Albert, and Peggy Mok. “Lexical Tone.” The Cambridge Handbook of Phonetics, Cambridge University Press, 2021. Read the sourceWhat lexical tone is and how its phonetic realization varies
• [3]“Tone Sandhi.” Introduction to Phonetics, Hong Kong Polytechnic University. Read the sourceMandarin third-tone sandhi and the rules for 一 and 不
• [4]“Mandarin Tone Change Rules.” Visit Beijing, 2024. Read the sourceThe half-third tone and everyday Mandarin tone changes
• [5]“The Role of Phonological Alternation in Speech Production: Evidence from Mandarin Tone Sandhi.” Research article archived in PubMed Central. Read the sourceT3 → T2 rule, word production, and incomplete acoustic neutralization
• [6]Speer, Shari R., Chi-Lin Shih, and Maria L. Slowiaczek. “Prosodic Structure in Language Understanding: Evidence from Tone Sandhi in Mandarin.” Language and Speech, 1989. Read the sourcePhrase grouping and how listeners interpret tone sandhi
• [7]“Glottalization of Taiwan Min Checked Tones.” Journal of the International Phonetic Association, Cambridge University Press. Read the sourceNon-final tone sandhi, tonal chains, and pitch-number examples in Taiwan Min
• [8]“Structure-Dependent Tone Sandhi in Real and Nonce Disyllables in Shanghai Wu.” Journal of Phonetics, Elsevier. Read the sourceLeft-dominant tone sandhi in Shanghai Wu
• [9]“An Acoustic Study of Contextual Tonal Variation in Tianjin Mandarin.” Journal of Phonetics, Elsevier. Read the sourceThe difference between tonal coarticulation and phonological tone sandhi
• [10]Zhang, Jie. “Tonal Processes Defined as Tone Sandhi.” The Cambridge Handbook of Chinese Linguistics, Cambridge University Press, 2022. Read the sourceTone-sandhi typology, phonological theory, processing, and acquisition