Stop diphthonging! How English speakers can finally nail the Spanish “o”

May 23, 2026

If your Spanish no sounds like the English no — it doesn’t. And that single habit is colouring almost every word you say.


What you’re doing without realising it

In American English, the vowel in words like no, go or home is not a pure [o] . It’s a diphthong: it starts as [o] and glides towards [ʊ] as your lips close. In phonetic notation it’s written [oʊ] — two sounds fused into one. You can feel this if you say no slowly and watch your lips: they start open and round, then close slightly at the end.

In British English the diphthong is slightly different — transcribed as [əʊ] — but the glide is still there.

Spanish has neither. The Spanish [o] is a pure vowel: one position, one sound, no movement.


The technical difference

American EnglishBritish EnglishSpanish
IPA symbol[oʊ][əʊ][o]
TypeDiphthongDiphthongPure vowel
Lip movementStarts open, closesStarts central, closesNone

Why does this matter?

The diphthong is so automatic that most speakers don’t notice it — until they hear themselves on a recording in Spanish. It affects every word ending in -o (gato, poco, libro), every monosyllable (no, yo), and cognates like foto, moto or radio, which are the most dangerous because your brain switches to English phonetics automatically when it recognises a familiar word.


A reference point you already know

Think of the vowel sound in the exclamation oh! — said short and with surprise, without letting it drag. That brief, stable moment before your lips start to close is exactly the Spanish [o]. Stop the sound there.


The mirror test

Say no in Spanish and watch your lips.

  • Lips close at the end → English diphthong. Correct it.
  • Lips stay still → Spanish [o]. That’s it.

Words to practise

  • foto [ˈfo.to] — photo
  • gato [ˈga.to] — cat
  • poco [ˈpo.ko] — a little
  • moto [ˈmo.to] — motorbike
  • libro [ˈli.βɾo] — book

Train your ear – Words


Train your ear – Sentences