학습하다

• Tensing (경음화) — ㄱ ㄷ ㅂ ㅅ ㅈ after a ㄱ ㄷ ㅂ sound become tense (ㄲ ㄸ ㅃ ㅆ ㅉ).
• 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.