Almost all learners of a second language have to produce sounds which are not found in their own language and which they may not have even heard before embarking on learning that second language.
Korean has three series of oral stops (sounds like English p, b, t, d, k and g), affricates (sounds like English ch and j) and fricatives (sounds like English s and z), but the differences between them are sometimes confusing for learners of Korean as a second language. Definitely, one series (ㅂㄷㅈㅅㄱ) is unvoiced and unaspirated (sometimes called ‘plain’ or ‘lax’), another (ㅍ ㅌ ㅊ ㅋ) is unvoiced and aspirated, but every source I’ve read has a different explanation for the third (ㅃ ㄸ ㅉ ㅆ ㄲ). These are not just ‘double letters’ like English spelling has; they are distinct (but obviously related) sounds which make distinct (and usually totally unrelated) words.
For an English speaker, there are issues with the first and second series of sounds (which I may write about at some future time) but during my masters study I wrote a short summary of the explanations I had found for the third, which I copy, paste and slightly edit here.
Korean made easy for beginners (written by a Korean) calls them “tensed … pronounced with an explosive sound (a sound produced by your almost-closed vocal chords vibrating as you let the air out”.
Survival Korean (written by an American) calls them “double [or] hard … kind of like saying the word when you’re angry”.
Survival Korean vocabulary (written by a Korean) calls them “double … harder and thicker … maybe the hardest element of Korean pronunciation for English speakers to hear and mimic”.
The handbook of the International Phonetic Association gives no explanation, but uses the symbols /p/, /ph/ (the ‘h’ should be superscript, which I can’t seem to do in the text editor here) and /b/ and their equivalents, which is misleading. It gives:
ㅂ as /b/ (and equivalents) but in IPA these are voiced sounds
ㅍ as /ph/ (and equivalents) which I understand is correct
ㅃ as /p/ (and equivalents) but in IPA these are simply unvoiced and unaspirated; also, there is no element of ‘tense’ .
The textbook for my masters unit on Asian languages (written by a former professor at that university) explains that they are “produced with some kind of muscular tension (causing a stiffening of the vocal folds) … glottalized .. tensed”. He uses the symbol ’ , which is the IPA for ejectives (which are different sounds than in Korean), but the Americanist phonetic notation for glottalization (again, very different sounds).
[edit: this video (which I found just after I posted this) explains ejectives. He starts off by saying: “An ejective is when you eject a sound from your mouth with some extra venom and pop.” which might make it the same sounds as I am discussing here, but the sound he produces at the end is nothing like the Korean sound.]
The Wikipedia article on Korean phonology says: “The IPA symbol ⟨◌͈⟩ is used to denote the tensed consonants /p͈/, /t͈/, /k͈/, /t͈ɕ/, /s͈/.” The Extended IPA character set in the IPA handbook calls this diacritic “stronger articulation”.
The course coordinator for the phonetics and phonology course wrote in an informal discussion: “I don’t know Korean well myself, but I gather the ‘tense’ stops are made with a constricted layngeal setting.”
So, broad agreement that there’s something very different about these sounds, but no definitive explanation. Fortunately, those sounds are relatively rare in Korean words, and foreigners speaking Korean can usually get away with simply pronouncing them louder. Context usually helps: if I go into a bakery, I am more likely to be saying 빵 (bbang, bread) than 방 (bang, room), and vice versa in a hotel. But sometimes two words may be more-or-less equally plausible. In my Korean class on Wednesday, the vocabulary was ‘everyday activities’, most of which I already knew. Two of the words were 사다 (sada, to buy) and 싸다 (ssada, to be cheap); I could plausibly say to a shop-owner ‘사요’ (effectively, ‘I will buy this’) or ‘싸요’ (effectively, ‘This is cheap’ (viz commenting, without actually buying it)). I could even say ‘싸요, 사요’.
It’s not just me. At times, teaching ESL in Australia, the idea of ‘sounds which exist in one language but don’t in another’ cropped up. If I had a Korean or Korean-speaking Chinese student in the class at the time, I would get them to say 방 and 빵. Students from every other country unhesitatingly said that 빵 was simply 방 said louder. It’s not – it is a different and totally unrelated word.
PS 22 October. Soon after posting this, I developed a tickle in my throat which degenerated into a very sore throat which felt like turning into a cold. I went to a mini-supermarket, checked my mobile phone translator app and said ‘꿀 있어요?’ (kkul isseoyo? – Do you have honey?). The sales attendant looked blank, I tried again, she continued to look blank, I checked the word for bee then said 벌 (beol), she looked blank, I mimed spreading honey on bread, she looked blank, I rang my wife in Australia, she said the word to the woman who instantly brightened, said ‘oh, 꿀!’ then led me to where the honey is (next to the coffee!). The bottles say ‘동서벌꿀’ (dong-seo beol kkuul – east-west bee honey) (or possibly ‘cohabitation bee honey’).
As a result of battling the cold (successfully, it turned out), I missed last week’s Korean class. This week I told the teacher this story, and she instantly responded with ‘honey’ when I said 꿀, but as a Korean teacher, she’s more used to hearing foreigners pronounce Korean than the average mini-supermarket attendant is. (By the way, this honey’ is not used a term of endearment. The equivalent to the term of endearment ‘honey’ is 여보 (yeobo).)