There are several sound change rules of ㅎ you should keep in mind. Most of all, – 하다 [hada] is the most commonly used verb form in Korean. If you just skip these rules, you would likely miss big things while listening.
Let me explain them with some Korean words.
① Silent ㅎ
Between two vowels, the sound of ㅎ is usually weakened, almost silent.
좋아요 [조아요] [joayo] good, fine
넣어요 [너어요] [neoeoyo] to put in
놓아요 [노아요] [noayo] to put down
② ㅎ + ㄱ,ㄷ,ㅂ,ㅈ = ㅋ,ㅌ,ㅍ,ㅊ
ㄱ,ㄷ,ㅂ,ㅈ + ㅎ = ㅋ,ㅌ,ㅍ,ㅊ
When ㄱ,ㄷ,ㅂ, and ㅈ are located before or after ㅎ, the sounds shift to the harder counterparts ㅋ,ㅌ,ㅍ, and ㅊ respectively. As you know, ㅎ is one of the aspirated consonants. For aspirated consonants, speakers should put out the air out of the mouth heavily. This characteristic makes the adjacent consonant also aspirated : ㄱ,ㄷ,ㅂ,ㅈ ⇒ ㅋ,ㅌ,ㅍ,ㅊ.
어떻게 [어떠케] [eotteke] how
좋다 [조타] [jota] good, fine
넣다 [너타] [neota] to put in
놓다 [노타] [nota] to put down
그렇지만 [그러치만] [geureochiman] but, however
북한 [부칸] [bukan] North Korea
축하하다[추카하다] [chukahada] to congratulate
대답하다 [대다파다] [dedapada] to reply, to answer
입학하다 [이팍카다] [ipak-kada] to enter a school
③ ㅎ + ㅅ =ㅆ
When ㅎ comes before ㅅ, ㅅ becomes pronounced like ㅆ.
좋습니다 [조씁니다] [josseubnida] good, fine
넣습니다 [너씁니다] [neosseubnida] to put in
놓습니다 [노씁니다] [nosseubnida] to put down
④ ㅅ + ㅎ = ㅌ
Keep in mind ㅅ is normally pronounced like ㄷ at the end of a syllable (받침). So, when ㅅ becomes before ㅎ, it also behaves like ㄷ. As a result, when ㅅ is followed by a ㅎ, it becomes pronounced like ㅌ as mentioned above.
못하다 [모타다] [motada] can’t, unable to
못합니다 [모탑니다] [motabnida] can’t, unable to
잘못하다 [잘모타다] [jalmotada] to do something incorrectly, to err, to make a mistake
Please make the ㅎ sound rule yours. If you are familiar with them, they would definitely help improve your Korean listening and speaking skills as well as your proper pronunciation.
- Taylor I, Taylor M. Writing And Literacy In Chinese, Korean, And Japanese. Amsterdam: John Benjamins Pub. Co.; 1995.
- Shin J, Kiaer J, Cha J. The Sounds Of Korean. Cambridge: Cambridge University Press; 2012.
- En.wikibooks.org. Korean/Essential Pronunciation Rules – Wikibooks, open books for an open world. 2015. Available at: https://en.wikibooks.org/wiki/Korean/Essential_Pronunciation_Rules. Accessed December 16, 2015.