Why Koreans Don't Pronounce What They Write: 6 Sound Change Rules

The hidden rules that turn 감사합니다 into [감사함니다] — understand Korean pronunciation once and for all.

Why Written Korean ≠ Spoken Korean

If you've ever heard a Korean word and thought 'that doesn't match the spelling at all,' you're not wrong. Korean has six major sound change rules that alter pronunciation depending on which consonants sit next to each other. These rules are completely predictable — once you learn them, you can pronounce any word correctly, even ones you've never seen before.

Sound changes happen at syllable boundaries — where one syllable's batchim meets the next syllable's initial consonant.

1. Liaison (연음법칙): The Batchim Slides Over

When a syllable ending in a batchim is followed by ㅇ (silent placeholder), the batchim moves over and becomes the initial consonant of the next syllable. 한국어 → [한구거]. The ㄱ batchim of 국 slides to replace the silent ㅇ of 어. This is the most basic and common sound change.

Liaison is why reading Korean feels so different from hearing it. The syllable boundaries shift in speech.

2. Nasalization (비음화): Stops Become Nasal

When a stop consonant (ㄱ,ㄷ,ㅂ) sits before a nasal consonant (ㄴ,ㅁ), the stop becomes nasal too. ㄱ→[ㅇ], ㄷ→[ㄴ], ㅂ→[ㅁ]. This is why 합니다 sounds like [함니다] — the ㅂ before ㄴ becomes [ㅁ]. And 국물 sounds like [궁물] — the ㄱ before ㅁ becomes [ㅇ].

3. Tensification (경음화): Consonants Get Tense

After a stop batchim (ㄱ,ㄷ,ㅂ), the following plain consonant becomes its tense version. ㄱ+ㄱ→[ㄱㄲ], ㄱ+ㄷ→[ㄱㄸ], etc. So 학교 sounds like [학꾜] and 국밥 sounds like [국빱]. The stop batchim 'tenses up' the next consonant.

4. Palatalization (구개음화): ㄷ/ㅌ + ㅣ = ㅈ/ㅊ

When ㄷ or ㅌ batchim meets the vowel ㅣ, they change to ㅈ or ㅊ. 같이 (together) → [가치], 굳이 (stubbornly) → [구지]. The tongue position shifts to the palate (roof of the mouth).

5. ㅎ-Aspiration (ㅎ축약): ㅎ Adds Breath

When ㅎ meets a plain consonant (ㄱ,ㄷ,ㅂ,ㅈ), they merge into an aspirated consonant. ㅎ+ㄱ→ㅋ, ㅎ+ㄷ→ㅌ, ㅎ+ㅂ→ㅍ, ㅎ+ㅈ→ㅊ. So 좋다 → [조타] and 놓고 → [노코]. The ㅎ disappears but leaves its breath behind.

6. Liquidization (유음화): ㄴ Becomes ㄹ

When ㄴ and ㄹ meet each other (in either order), the ㄴ usually becomes ㄹ. 신라 → [실라], 연락 → [열락]. Both consonants end up as ㄹ. This makes speech flow more smoothly.

Examples

합니다 — ham-ni-da — does/is (formal)

학교 — hak-kkyo — School

같이 — ga-chi — Together

좋다 — jo-ta — Good

신라 — sil-la — Silla (dynasty)

독립 — dong-nip — Independence