French Nasal Vowels, Explained (Bon, Blanc, Vin, Un)

What’s actually happening physically

For an ordinary vowel, the soft palate at the back of the mouth stays raised, sealing off the nasal cavity so all the air goes out through the mouth. For a nasal vowel, that seal partly opens, letting air resonate through the nose at the same time as the mouth shapes the vowel. English does this involuntarily right before an "n" or "m" (say "on" and feel it), but it never treats the nasalized version as a separate, meaningful sound the way French does — in French, bon (good) and beau (beautiful) are distinguished partly by nasalization, not just by spelling.

The four nasal vowels, and how to tell them apart

• On (as in bon): a nasalized, rounded back vowel — lips rounded, tongue pulled back.
• An/En (as in blanc, français): a nasalized open vowel, mouth more open than for "on," lips not rounded.
• In (as in vin, main): a nasalized front vowel, closer to an English "a" in "cat" said through the nose.
• Un (as in un, brun): the rarest of the four in modern spoken French — many speakers merge it with "in" — a nasalized rounded front vowel when kept distinct.

How to actually build the sounds

Say an ordinary French oral vowel first, then let a small amount of air leak through the nose while holding the same mouth shape — resist the urge to add an English "n" sound at the end, since that's a consonant, not nasalization, and it's the single most common mistake English speakers make here. Comparing your attempt against a reference voice in your own register makes it easier to judge whether the nasal quality itself is right, rather than getting distracted by a pitch difference on top of an already-unfamiliar sound.