먹먹하다

• Nasalization (비음화) — ㄱ ㄷ ㅂ before ㄴ ㅁ turn into ㅇ ㄴ ㅁ (and ㄹ after ㅁ ㅇ ㄱ ㅂ becomes ㄴ).
• Aspiration (격음화) — ㅎ next to ㄱ ㄷ ㅂ ㅈ makes the harder sound ㅋ ㅌ ㅍ ㅊ.

Standard pronunciation of the word on its own. Sounds can shift a little inside a sentence.