French /z/ vs /s/
poison vs poisson: single s between vowels is a z, not the English s rule

French poison (poison) and poisson (fish) look almost identical in writing but mean very different things, and the rule is entirely in the double s. A single s between two vowels is /z/. A double ss stays /s/. Miss this rule and you will order fish and get served something worse.

The drill above is five ABX rounds of /z/ vs /s/ in real French words. Your ear learns the voicing cue, and your brain starts reading French spelling the way French readers do.

👅Tongue tip near the ridge
🔈Only voicing differs
📝Single s = /z/ between vowels
🐟Real pairs: poison, poisson
Can you hear the difference?
How it works: You'll hear sound A, sound B, then a mystery sound X. Choose whether X sounds like A or B. Words are revealed after you answer.
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Listen carefully...

Mystery sound

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The problem

Why French /z/ and /s/ hide inside French spelling

/z/ and /s/ are both alveolar fricatives: the tongue tip sits near the bumpy ridge behind your upper teeth, and a narrow jet of air hisses through. The only difference is voicing. /z/ buzzes. /s/ hisses cleanly. Pronunciation-wise, most learners can already make both sounds. The trouble is knowing when French is using which one.

Here is the rule that fixes most confusion: a single s between two vowels is pronounced /z/. So maison is /mɛzɔ̃/, not /mɛsɔ̃/. Chose is /ʃoz/. Rose is /ʁoz/. Raison is /ʁɛzɔ̃/. To get the /s/ sound between vowels, French doubles the letter: poisson, assez, tasse, dessert. That is also why poison (/pwazɔ̃/, one s, = /z/) and poisson (/pwasɔ̃/, two s, = /s/) mean such different things.

Learners whose native language does not enforce this spelling rule often read every s as /s/, which produces words like puh-sohn-AHSS for maison. Once you internalize single s = /z/ and double s = /s/, your French reading improves overnight.

What happens without training
  • ✗ You say poisson (fish) but mean poison (poison)
  • ✗ You say dessert (dessert) but mean désert (desert)
  • ✗ You say coussin (cushion) but mean cousin (cousin)
  • ✗ You read every s as /s/ and never voice single s
What changes with ear training
  • ✓ Single s between vowels becomes /z/ automatically
  • ✓ Rose, chose, maison, raison sound native
  • ✓ Poison and poisson stop being the same word
Production guide

How to produce /z/ and /s/

/z/French "z", as in poison, rose, maison
  1. 1. Tongue tip near the ridge behind your upper teeth, not touching.
  2. 2. Start voicing first.
  3. 3. Push a narrow stream of air through the small gap while the buzz continues.
  4. 4. It should feel exactly like the English z in zebra.
Anchor words: poison, rose, maison, chose, raison, zone
/s/French "s", as in poisson, sel, classe
  1. 1. Same tongue placement, same narrow gap.
  2. 2. No voicing. Pure breath.
  3. 3. A clean hiss, no buzz at all.
  4. 4. It should feel like the English s in see.
Anchor words: poisson, sel, classe, sept, sous, son
The spelling rule that saves you

One s between vowels is /z/. Two s between vowels is /s/. Examples: rose /ʁoz/ vs grosse /ɡʁos/, chose /ʃoz/ vs chasse /ʃas/, poison /pwazɔ̃/ vs poisson /pwasɔ̃/. Remember this rule and ninety percent of z vs s confusion disappears.

The throat buzz test

Put your fingers on your throat. Say a long zzzzz. Strong vibration. Say a long ssssss. Nothing. Switch back and forth rapidly. You are feeling the voicing cue turn on and off. That is exactly what French is asking you to control, consistently.

Click to hear

Minimal pairs: tap each word to hear it

Real French words that differ only in the /z/ vs /s/ contrast. Click each one to compare.

French "z" /z/
French "s" /s/
poison
↔
fish
desert
↔
dessert
cousin
↔
cushion
twelve
↔
soft / sweet (fem.)
zone
↔
rings / sounds
rose / pink
↔
nag / mean (adj.)
More /z/ words (spelled "z")
zonerosechosemaisonraisonpoisoncousindouzetreizequatorzezérozoo
More /s/ words (spelled "s")
poissonselclasseseptsoussonsursiasseztassebassecasse
Common questions

Frequently asked

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