Pronunciation Guide
How tone change works for 一 and 不
一 and 不 do not keep the same citation tone in every context. Their spoken tone changes according to what comes next, especially before fourth tones.
Short answer
一 and 不 change tone based on the following syllable, especially before fourth tones where they usually become rising tones.
Why learners miss it
Learners often practice 一 and 不 in isolation, so they keep the dictionary tone even when natural Mandarin changes the contour in phrases.
Self-test
Record 一个, 一杯, and 我不是, then check whether 一 and 不 shift tone before the next syllable.
How to shape the sound
- Before a fourth tone, 一 usually rises to yí and 不 usually rises to bú.
- Before first, second, or third tones, 一 often falls as yì.
- Practice the whole phrase, not the isolated character, because the sandhi belongs to the chunk.
Common mistakes
- Saying yī gè instead of yí gè.
- Keeping 不 as bù before 是 or 要.
- Memorizing isolated tones without connecting them to phrase context.
Practice with example words
Practice with example sentences
FAQ
Why does 一 sometimes sound like yí and sometimes yì?
The tone changes to fit the contour of the next syllable and make the phrase easier to say naturally.
Is 不 always bú before a fourth tone?
That is the core pattern in standard Mandarin and the one learners should master first.
Related pronunciation guides
How to pronounce zh, ch, sh, and r in Chinese
A practical guide to Mandarin retroflex initials with tongue position tips, common substitutions, and sample words.
z c s vs zh ch sh: Mandarin pronunciation difference
Learn the contrast between flat alveolar initials and retroflex initials with tongue-position cues, common mistakes, and minimal-pair style drills.
How to pronounce j, q, and x in Mandarin
An English-first explanation of Mandarin j, q, and x with lip shape, tongue placement, and easy starter examples.