The cot–caught merger!

When /ɑ/ and /ɔ/ collapse into a single vowel

A large share of American English speakers no longer distinguish /ɑ/ from /ɔ/: for them cot and caught sound exactly alike. Others keep the two apart. Neither is wrong — what matters is recognizing both when you listen.

How it's made

• 👄 Mouth: in a merged accent, one single open position serves both words.
• 👅 Tongue: back and low, unchanged between cot and caught.
• 🔊 Voice: in an unmerged accent, the difference is whether the lips round.

You hear it in: cot / caught · stock / stalk · don / dawn · not / naught

⚠️ The typical Spanish-speaker mistake: assuming there's one correct pronunciation, and freezing when a native speaker merges the two sounds.

By the end you'll be able to: understand speakers with and without the merger, and decide deliberately which model you're imitating.