The short answer: «au» and aux» are pronounced exactly the same in French: both sound like the closed O /o/. The difference is purely grammatical, not phonetic.
- au = contraction of à + le (masculine singular) → «to the / at the»
- aux = contraction of à + les (plural, any gender) → «to the / at the» (plural)
Because the final x in aux is silent, they sound identical. Only context tells you whether it’s singular or plural.
📚 Examples: au (singular) vs aux (plural)
1. With places / locations
| Singular (au) | Plural (aux) |
|---|---|
| Je vais au marché. (to the market) | Je vais aux marchés. (to the markets) |
| Il habite au Canada. (in Canada) | Ils habitent aux États-Unis. (in the US – plural because États-Unis is plural) |
| Elle est au bureau. (at the office) | Elles sont aux bureaux. (at the offices) |
| On va au cinéma. (to the cinema) | On va aux cinémas. (to the cinemas) |
2. With people / groups
| Singular | Plural |
|---|---|
| Parle au professeur. (speak to the teacher) | Parle aux professeurs. (speak to the teachers) |
| J’écris au directeur. (I write to the director) | J’écris aux directeurs. (to the directors) |
| Offre un cadeau au enfant. (to the child) – but enfant is masculine, so au | Offre un cadeau aux enfants. (to the children) |
3. In common expressions
| Expression with au | With aux |
|---|---|
| au revoir (goodbye – singular “to seeing you again”) | aux revoirs (rare – used only when saying multiple goodbyes) |
| au début (at the beginning) | aux débuts (at the beginnings) |
| au fait (by the way) | aux faits (to the facts – not common) |
| au secours ! (help – singular cry) | aux secours (to the rescues – not typical) |
4. Minimal pair sentences (same pronunciation, different meaning)
Au restaurant, on mange bien.
Aux restaurants, on mange bien aussi.
(At the restaurant / At restaurants – same /o/)J’ai parlé au voisin.
J’ai parlé aux voisins.
(/o vwɛ.zɛ̃/ vs /o vwɛ.zɛ̃/ – identical sound, but plural voisins is understood from context or spelling)
🧠 Memory trick
- au = singular → think of a = 1 letter → 1 thing.
- aux = plural → think of the x = like an “x” marking a group (extra letters for extra things).
But in speaking, you never need to worry: just say /o/ for both.
⚠️ Common mistake for learners
Because au and aux sound the same, beginners sometimes write au when they mean aux (or vice versa). In writing, remember:
- Use au before a masculine singular noun (le).
- Use aux before any plural noun (les).
Example:
✔️ Je pense au projet (le projet = singular masculine).
✔️ Je pense aux projets (les projets = plural).
Let me know if you’d like a full drill exercise with audio tips!
