Korean phonology

This article is a technical description of the phonetics and phonology of Korean. Unless otherwise noted, statements in this article refer to South Korean standard language based on the Seoul dialect.

Morphophonemes are written inside double slashes, phonemes inside slashes , and allophones inside brackets.

Consonants
Korean has 19 consonant phonemes.

For each plosive and affricate, there is a three-way contrast between unvoiced segments, which are distinguished as plain, tense, and aspirated.
 * The "plain" segments, sometimes referred to as "lax" or "lenis," are considered to be the more "basic" or unmarked members of the Korean obstruent series. The "plain" segments are also distinguished from the tense and aspirated phonemes by changes in vowel quality, including a relatively lower pitch of the following vowel.
 * The "tense" segments, also referred to as "fortis," "hard," or "glottalized," have eluded precise description and have been the subject of considerable phonetic investigation. In the Korean alphabet as well as all widely used romanization systems for Korean, they are represented as doubled plain segments: ㅃ pp, ㄸ tt, ㅉ jj, ㄲ kk. As it was suggested from the Middle Korean spelling, the tense consonants came from the initial consonant clusters sC-, pC-, psC-.
 * The "aspirated" segments are characterized by aspiration, a burst of air accompanied by the delayed onset of voicing.

Korean syllable structure is maximally CGVC, where G is a glide. (There is a unique off-glide diphthong in the character 의 that combines the sounds and  creating ). Any consonant except may occur initially, but only  may occur finally. Sequences of two consonants may occur between vowels.

Plain
are voiced between sonorants (including all vowels and certain consonants) but voiceless elsewhere. Among younger generations, they may be just as aspirated as in initial position; the primary difference is that vowels following the plain consonants carry low tone.

Aspirated
are strongly aspirated, more so than English voiceless stops. They generally do not undergo intervocalic voicing, but a 2020 study reports that it still occurs in around 10~15% of cases. It is more prevalent among older male speakers who have aspirated stops voiced in as much as 28% of cases.

Tense
The IPA diacritic ⟨◌͈⟩, resembling a subscript double straight quotation mark, shown here with a placeholder circle, is used to denote the tensed consonants. Its official use in the Extensions to the IPA is for strong articulation, but is used in literature in the context of Korean phonology for faucalized voice. The Korean consonants also have elements of stiff voice, but it is not yet known how typical that is of faucalized consonants. Sometimes the tense consonants are marked with an apostrophe, ⟨ʼ⟩, but that is not IPA usage; in the IPA, the apostrophe indicates ejective consonants. Some works use full-size or small  before tensed consonants, this notation is generally used to denote pre-glottalization. Asterisk after a tensed consonant is also used in literature.

They are produced with a partially constricted glottis and additional subglottal pressure in addition to tense vocal tract walls, laryngeal lowering, or other expansion of the larynx.

An alternative analysis proposes that the "tensed" series of sounds are (fundamentally) regular voiceless, unaspirated consonants: the "lax" sounds are voiced consonants that become devoiced initially, and the primary distinguishing feature between word-initial "lax" and "tensed" consonants is that initial lax sounds cause the following vowel to assume a low-to-high pitch contour, a feature reportedly associated with voiced consonants in many Asian languages (such as Shanghainese), whereas tensed (and also aspirated) consonants are associated with a uniformly high pitch.

Vowels before tense consonants (as well as aspirated) tend to be shorter than before lax stops.

The Gyeongsang dialect is known for realization of tense ㅆ ss as plain ㅅ s.

Fricatives
ㅎ h does not occur in final position, though the sound does occur at the end of non-final syllables, where it affects the following consonant. (See below.) Intervocalically, it is realized as voiced, and after voiced consonants it is either or silent.

The analysis of as phonologically plain or aspirated has been a source of controversy in the literature. Similarly to plain stops, it shows moderate aspiration word-initially but no aspiration word-medially. It also often undergoes intervocalic voicing. But similar to aspirated stops, it triggers high pitch in the following vowel.

Word-initial aspiration, intervocalic voicing, and higher pitch of the following vowels are shared qualities in Korean fricatives and.

Sonorants
Sonorants resemble vowels in the sense that plain stops become voiced between a sonorant or a vowel and another vowel.

ㅁ, ㄴ tend to be denasalized word-initially.

ㅇ ng does not occur in initial position, reflected in the way the Hangul jamo ㅇ has a different pronunciation in the initial position to the final position. These were distinguished when Hangul was created, with the jamo ㆁ with the upper dot and the jamo ㅇ without the upper dot; these were then conflated and merged in both the North Korean and South Korean standards. can technically occur syllable-initially, as in 명이, which is written as, but pronounced as.

ㄹ is an alveolar flap  between vowels or between a vowel and an. It is or  at the end of a word, before a consonant other than, or next to another ; in these contexts, it is palatalized to  before  and before palatal consonant allophones. There is free variation at the beginning of a word, where this phoneme tends to become before most vowels and silent before, but it is commonly  in English loanwords. Geminate is realized as, or as  before.

In native Korean words, ㄹ r does not occur word initially, unlike in Chinese loans (Sino-Korean vocabulary). In South Korea, it is silent in initial position before and, pronounced  before other vowels, and pronounced  only in compound words after a vowel. The prohibition on word-initial r is called the "initial sound law" or dueum beopchik (두음법칙). Initial r is officially spelled with ㄹ in North Korea, but is often pronounced the same way as it is in South Korea.


 * "labour" (勞動) – North Korea: rodong (로동), South Korea: nodong (노동)
 * "history" (歷史) – North Korea: ryŏksa (력사), South Korea: yeoksa (역사)

This rule also extends to ㄴ n in many native and all Sino-Korean words, which is also lost before initial and  in South Korean; again, North Korean preserves the  phoneme there.


 * "female" (女子) – North Korea: nyŏja (녀자), South Korea: yeoja (여자)

In both countries, initial r in words of foreign origin other than Chinese is pronounced. Very old speakers may pronounce word-initial r as even in Western loanwords, e.g. in "lighter" 라이터.

When pronounced as an alveolar flap, ㄹ is sometimes allophonic with , which generally does not occur elsewhere.

The features of consonants are summed up in the following table.

Clusters
Morphemes may also end in CC clusters, which are both expressed only when they are followed by a vowel. When the morpheme is not suffixed, one of the consonants is not expressed; if there is a, which cannot appear in final position, it will be that. Otherwise it will be a coronal consonant (with the exception of, sometimes), and if the sequence is two coronals, the voiceless one will drop, and  or  will remain. either reduces to (as in 짧다  "to be short" ) or to  (as in 밟다  "to step" ); 여덟  "eight" is always pronounced 여덜 even when followed by a vowel-initial particle. Thus, no sequence reduces to in final position.


 * {| class="wikitable"

! Sequence ! ㄳ gs ! ㄺ lg ! ㄵ nj ! ㄶ nh ! ㄽ ls ! ㄾ lt ! ㅀ lh ! colspan="2" |ㄼ lb ! ㅄ bs ! ㄿ lp ! ㄻ lm ! Medial allophone ! Final allophone
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 * colspan="2" |
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 * }
 * }

When such a sequence is followed by a consonant, the same reduction takes place, but a trace of the lost consonant may remain in its effect on the following consonant. The effects are the same as in a sequence between vowels: an elided obstruent will leave the third consonant fortis, if it is a stop, and an elided will leave it aspirated. Most conceivable combinations do not actually occur; a few examples are =,  = ,  = ,  = ,  = ,  = ; also  = , as  has no effect on a following , and  = , with the  dropping out.

When the second and third consonants are homorganic obstruents, they merge, becoming fortis or aspirate, and, depending on the word and a preceding, might not elide: is.

An elided has no effect:  =,  = ,  = ,  = ,  = ,  = ,  = ,  = ,  = ,  = ,   =.

Positional allophones
Korean consonants have three principal positional allophones: initial, medial (voiced), and final (checked). The initial form is found at the beginning of phonological words. The medial form is found in voiced environments, intervocalically (immediately between vowels), and after a voiced consonant such as n or l. The final form is found in checked environments such as at the end of a phonological word or before an obstruent consonant such as t or k. Nasal consonants (m, n, ng) do not have noticeable positional allophones beyond initial denasalization, and ng cannot appear in this position.

The table below is out of alphabetical order to make the relationships between the consonants explicit:

All obstruents (stops, affricates, fricatives) become stops with no audible release at the end of a word: all coronals collapse to, all labials to , and all velars to. Final ㄹ r is a lateral or.

Palatalization
The vowel that most affects consonants is, which, along with its semivowel homologue , palatalizes and  to alveolo-palatal  and  for most speakers (but see differences in the language between North Korea and South Korea).

ㅈ, ㅊ, ㅉ are pronounced in Seoul, but typically pronounced  in Pyongyang. Similarly, are palatalized as  before  in Seoul. In Pyongyang they remain unchanged. This pronunciation may be also found in Seoul Korean among some speakers, especially before back vowels.

As noted above, initial is silent in this palatalizing environment, at least in South Korea. Similarly, an underlying or  at the end of a morpheme becomes a phonemically palatalized affricate  or, respectively, when followed by a word or suffix beginning with  or  (it becomes indistinguishable from an underlying ), but that does not happen within native Korean words such as   "where?".

is more affected by vowels, often becoming an affricate when followed by or :,. The most variable consonant is, which becomes a palatal before  or , a velar  before , and a bilabial  before ,  and.

In many morphological processes, a vowel before another vowel may become the semivowel. Likewise, and, before another vowel, may reduce to. In some dialects and speech registers, the semivowel assimilates into a following  or  and produces the front rounded vowels  and.

Consonant assimilation
As noted above, tenuis stops and are voiced after the voiced consonants, and the resulting voiced  tends to be elided. Tenuis stops become fortis after obstruents (which, as noted above, are reduced to ); that is, is pronounced. Fortis and nasal stops are unaffected by either environment, though assimilates to  after an. After, tenuis stops become aspirated, becomes fortis, and  is unaffected. is highly affected: it becomes after all consonants but  (which assimilates to the  instead) or another. For example, underlying (종로) is pronounced  (종노).

These are all progressive assimilation. Korean also has regressive (anticipatory) assimilation: a consonant tends to assimilate in manner but not in place of articulation: Obstruents become nasal stops before nasal stops (which, as just noted, includes underlying ), but do not change their position in the mouth. Velar stops (that is, all consonants pronounced in final position) become ; coronals  become, and labials  become. For example, (한국말) is pronounced  (한궁말) (phonetically ).

Before the fricatives, coronal obstruents assimilate to a fricative, resulting in a geminate. That is, is pronounced. A final assimilates in both place and manner, so that  is pronounced as a geminate (and, as noted above, aspirated if C is a stop). The two coronal sonorants, and, in whichever order, assimilate to , so that both  and  are pronounced.

There are lexical exceptions to these generalizations. For example, voiced consonants occasionally cause a following consonant to become fortis rather than voiced; this is especially common with and  as  and, but is also occasionally seen with other sequences, such as  ,   and.


 * 1) Velar obstruents found in final position: ㄱ g, ㄲ kk, ㅋ k
 * 2) Final coronal obstruents: ㄷ d, ㅌ t, ㅅ s, ㅆ ss, ㅈ j, ㅊ ch
 * 3) Final labial obstruents: ㅂ b, ㅍ p

The resulting geminate obstruents, such as, , , and (that is, , , , and ), tend to reduce  in rapid conversation. Heterorganic obstruent sequences such as and  may, less frequently, assimilate to geminates  and also reduce to.

These sequences assimilate with following vowels the way single consonants do, so that for example and  palatalize to  (that is, ) before  and ;  and  affricate to  and  before ;, , and  palatalize to  and  across morpheme boundaries, and so on.

Hangul orthography does not generally reflect these assimilatory processes, but rather maintains the underlying morphology in most cases.

Vowels
Most Standard Korean speakers have seven vowel phonemes.

Korean is phonetically.

The distinction between and  is lost in South Korean dialects—both are most commonly realized as, but some older speakers still retain the difference; as for North Korean, some works report the distinction to be robust. However, the data from one study suggests that while younger KCTV anchors try to produce them more or less distinctly, it is not clear whether that is learned or natural pronunciation, as they do so inconsistently. Notably, older anchor Ri Chun-hee and even Kim Jong-un both have and  merged.

In Seoul Korean, is produced higher than, while in North Korean dialects the two are comparable in height, and  is more fronted. In Gyeongsang dialect, and  once have merged into  in speech of older speakers, but they are distinct among young and middle-aged Daegu residents (they actually have the same vowels as Seoulites due to influence from Standard Korean).

In Seoul, is fronted, while  is raised, and both are almost the same height, though  is still more rounded. Due to this, alternative transcriptions like or  for, and  or  for  are proposed. In both varieties, is fronted away from, and in North Korean it is also lower, shifting more towards.

Korean used to have two additional phonemes, ㅚ and  ㅟ, but they are replaced by the diphthongs  and  by the majority of speakers.

Middle Korean had an additional vowel phoneme denoted by ᆞ, known as arae-a (literally "lower a"). The vowel merged with in all mainland varieties of Korean, but remains distinct in Jeju where it is pronounced.

Diphthongs and glides
Because they may follow consonants in initial position in a word—which no other consonant can do—and also because of Hangul orthography, which transcribes them as vowels, semivowels such as and  are sometimes considered to be elements of rising diphthongs rather than separate consonant phonemes.

In modern pronunciation, merges into  after a consonant. Some analyses treat as a central vowel and thus the marginal sequence  as having a central-vowel onset, which would be more accurately transcribed  or.

Modern Korean has no falling diphthongs, with sequences like being considered as two separate vowels in hiatus. Middle Korean had a full set of diphthongs ending in, but these monophthongized into modern-day front vowels in Early Modern Korean. This is the reason why the hangul letters ㅐ, ㅔ, ㅚ etc. are represented as back vowels plus i.

The sequences do not occur, and it is not possible to write them using standard hangul. The semivowel occurs only in the diphthong, and is prone to being deleted after a consonant.

Loss of vowel length contrast
Korean used to have a length distinction for each vowel, but this is now reported to be almost completely neutralized (though it is still prescriptive). Long vowels were pronounced somewhat more peripherally than short ones. As an exception, for most of the speakers who still utilize vowel length contrastively, long is actually.

Vowel length is a remnant of rising tone, first emerging in Middle Korean. It was preserved only in initial syllables and was often neutralized, particularly in the following cases:
 * In compound words:
 * 사람 "man", but
 * 눈사람 "snowman";
 * 벌리다 "to open, to spread", but
 * 떠벌리다 "to brag".
 * In most monosyllabic verbs when attaching a suffix starting with a vowel
 * 굶다 "to starve", but
 * 굶어 ;
 * 넣다 "to put", but
 * 넣으니 ,
 * or a suffix changing transitivity
 * 붇다 "to swell up", but
 * 불리다 "to soak";
 * 꼬다 "to twist", but
 * 꼬이다 "to be entangled".
 * There were exceptions though:
 * 얻다 "to obtain" still had long vowels in
 * 얻어 ;
 * 없다 "to not be" still had long vowels in
 * 없으니.

It has disappeared gradually among younger speakers, but some middle-aged speakers are still aware of it and can still produce it in conscious speech. The long–short merger has had two main aspects. The first is phonetic: The duration of long vowels in relation to short ones has reduced by a lot (from 2.5:1 in the 1960s to 1.5:1 in the 2000s). Some studies suggest that the length of all vowels is dependent on one's age (older speakers seem to exhibit a slower speech rate, and even their short vowels are produced relatively longer than those of younger speakers). The second aspect is lexical: The subset of words produced with long vowels has gotten smaller. Long vowels tend to be reduced most frequently in high-frequency words.

Vowel harmony
Traditionally, the Korean language has had strong vowel harmony; that is, in pre-modern Korean, not only did the inflectional and derivational affixes (such as postpositions) change in accordance to the main root vowel, but native words also adhered to vowel harmony. It is not universally prevalent in modern usage, but it remains in onomatopoeia, adjectives and adverbs, interjections, and conjugation. There are also other traces of vowel harmony in Korean.

There are three classes of vowels in Korean: "positive", "negative", and "neutral". The vowel ㅡ (eu) is considered both partially neutral and partially negative. The vowel classes loosely follow the negative and positive vowels; they also follow orthography. Exchanging positive vowels with negative vowels usually creates different nuances of meaning, with positive vowels representing diminutives and negative vowels representing exaggeration:


 * Onomatopoeia:
 * 퐁당퐁당 (pongdang-pongdang) and 풍덩풍덩 (pungdeong-pungdeong), light and heavy water splashing
 * Emphasized adjectives:
 * 노랗다 (norata) means plain yellow, while its negative, 누렇다 (nureota), means dark yellow
 * 파랗다 (parata) means plain blue, while its negative, 퍼렇다 (peoreota), means deep blue
 * Particles at the end of verbs:
 * 잡다 (japda) (to catch) → 잡았다 (jabatda) (caught)
 * 접다 (jeopda) (to fold) → 접었다 (jeobeotda) (folded)
 * Interjections:
 * 아이고 (aigo) and 어이구 (eoigu) expressing surprise, discomfort or sympathy
 * 아하 (aha) and 어허 (eoheo) expressing sudden realization and mild objection, respectively

Accent and pitch
In modern Standard Korean, in multisyllabic words the second syllable has high pitch that gradually comes down in subsequent syllables. The first syllable may have pitch as high as the second if it starts with a tense ㅃ, ㅉ, ㄸ, ㄲ, ㅆ or an aspirated ㅍ, ㅊ, ㅌ, ㅋ  consonant, as well as ㅅ, ㅎ, or lower rising pitch if it starts with plain ㅂ, ㅈ, ㄷ, ㄱ  or a sonorant ㅁ, ㄴ, ㄹ , including silent ㅇ, i.e. a vowel.

As early as 2004, researchers have posited that pitch and voicing are the actual distinguishing features between modern Korean consonants rather than the standard but seemingly ill defined "tense" vs "lax" theory. A 2013 study by Kang Yoon-jung and Han Sung-woo which compared voice recordings of Seoul speech from 1935 and 2005 found that in recent years, lenis consonants (ㅂㅈㄷㄱ), aspirated consonants (ㅍㅊㅌㅋ) and fortis consonants (ㅃㅉㄸㄲ) were shifting from a distinction via voice onset time to that of pitch change, and suggests that the modern Seoul dialect is currently undergoing tonogenesis. Kim Mi-Ryoung (2013) notes that these sound shifts still show variations among different speakers, suggesting that the transition is still ongoing. Cho Sung-hye (2017) examined 141 Seoul dialect speakers, and concluded that these pitch changes were originally initiated by females born in the 1950s, and has almost reached completion in the speech of those born in the 1990s. On the other hand, Choi Ji-youn et al. (2020) disagree with the suggestion that the consonant distinction shifting away from voice onset time is due to the introduction of tonal features, and instead proposes that it is a prosodically conditioned change.

Dialectal pitch accents
Several dialects outside Seoul retain the Middle Korean pitch accent system. In the dialect of Northern Gyeongsang, in southeastern South Korea, any syllable may have pitch accent in the form of a high tone, as may the two initial syllables. For example, in trisyllabic words, there are four possible tone patterns:
 * 메누리 ménuri 'daughter-in-law'
 * 어무이 eomú-i 'mother'
 * 원어민 woneomín 'native speaker'
 * 오래비 órébi 'elder brother'

Age differences
The following changes have been observed since the mid-20th century and by now are widespread, at least in South Korea.
 * Contrastive vowel length has disappeared. Although still prescriptive, in 2012, the vowel length is reported to be almost completely neutralized in Korean, except for a very few older speakers of the Seoul dialect, for whom the distinctive vowel length distinction is maintained only in the first syllable of a word. Even amongst those middle-aged speakers who retain the distinction, the phonetic contrast between a long vowel and a short vowel has shrunk to 1.5:1, compared to 2.5:1 recorded in the 1960s; additionally, the number of lexical items featuring long vowels has also reduced, with low-frequency words being more likely to retain long vowels than high-frequency ones. Vowel length has subsequently become a prosodic feature of the language, used mainly for emphasis, and placed typically on the first syllable of the word.
 * The mid front rounded vowel ( ㅚ) and the close front rounded vowel ( ㅟ), can still be heard in the speech of some older speakers, but they have been largely replaced by the diphthongs  and, respectively.  In a 2003 survey of 350 speakers from Seoul, nearly 90% pronounced the vowel ㅟ as.
 * The distinction between and  is lost in South Korean dialects. A number of homophones have appeared due to this change, and speakers may employ different strategies to distinguish them. For example, 내가  "I-subject" and 네가  "you-subject" are now pronounced as  and  respectively, with the latter having changed its vowel; 새 잔  "new glass" is pronounced with tensified  by some young speakers to not be conflated with 세 잔  "three glasses".

Some changes are still ongoing. They depend on age and gender, the speech of young females tends to be most innovative, while old males are phonologically conservative.
 * Plain stops in word-initial position are becoming as aspirated as "true" aspirated stops. They are still distinguished by their pitch, which indicates ongoing tonogenesis in Contemporary Seoul Korean.  This is however contested by studies which explain this as a prosodic feature.
 * Some words experience tensification of initial plain consonants, in both native and Sino-Korean words. It is proscribed in normative Standard Korean, but may be widespread or occur in free variation in certain words. Examples:
 * 가시 "1) thorn; 2) worm" is pronounced 까시
 * 닦다 "to polish" is pronounced 딲다
 * 조금 "a little" is pronounced 쪼금, 쬐끔
 * Tensification is very common in Western loanwords: 배지 "badge", 버스  "bus", 잼  "jam", although also proscribed in South Korea.