In casual American English, "A big grey dog" sounds like "uh BIHG GRAY DAHG". Three things happen here, and the headline one is the Unreleased Stops: the final stop consonant closes without a puff of air. Keep stressed words long, unstressed words short, and link the consonants forward into the vowels.
Now you try.
Read the sentence out loud at native speed. The mic stays on your device — nothing's uploaded.
What makes this sentence sound American.
In "dog", the "" is not released — the articulators get into position but hold without the burst of air. This is called the Unreleased Stops, the kind of sound shift that makes everyday speech feel effortless. It comes out as DAHG.
What's happening in this sentence.
Small tricks that turn a textbook sentence into how an American actually says it.
Common pronunciation mistakes in American English.
The textbook way isn't wrong — it's just not how anyone actually says it.
Releasing the final consonant with a puff of air.
In "dog", the "" is not released — the articulators get into position but hold without the burst of air. Air stops but there's no release burst — the articulators hold position.
Pronouncing the identical consonant twice.
The "" shared between "" and "" is held once, slightly longer, and released once instead of stopping and starting twice. Consonant is held slightly longer and released once (not said twice).
Pronouncing the function word too fully.
"a" is a function word — in connected speech, the full vowel reduces to a quick "" sound and consonants may simplify. Full vowel reduces to schwa /ə/ or other weak vowel. Consonants may simplify.