Hangul letters correspond closely to the phonemes of Late Middle Korean. The romanization most commonly used in linguistic writing on the history of Korean is the
Yale romanization devised by
Samuel E. Martin, which faithfully reflects the Hangul spelling. The tensed stops
pp,
tt,
cc and
kk are distinct phonemes in modern Korean, but in LMK they were allophones of consonant clusters. The tensed fricative
hh only occurred in a single verb root, 'to pull', and has disappeared in Modern Korean. The voiced fricatives , and occurred only in limited environments, and are believed to have arisen from
lenition of , and , respectively. They have disappeared in most modern dialects, but some dialects in the southeast and northeast retain , and in these words. The affricates
c,
ch and
cc were apical consonants, as in modern northwestern dialects, rather than palatals as in modern Seoul. Late Middle Korean had a limited and skewed set of initial clusters:
sp-,
st-,
sk-,
pt-,
pth-,
ps-,
pc-,
pst- and
psk-. It is believed that they resulted from
syncope of vowels
o or
u during the Middle Korean period. For example, the has () 'rice', which became LMK and modern . A similar process is responsible for many aspirated consonants. For example, the has () 'big', which became LMK and modern . Late Middle Korean had seven vowels: The precise phonetic values of these vowels are controversial. Six of them are still distinguished in modern Korean, but only the
Jeju language has a distinct reflex of
o, which was written with the now-archaic letter
aray a. In most other varieties it has merged with
a in the first syllable of a word and
u elsewhere. An exception is found in the
Yukjin Korean in the far northeast and in dialects along the south coast, where first-syllable
o has merged with
wo when adjacent to a labial consonant. LMK had rigid
vowel harmony, described in the
Hunminjeongeum Haerye by dividing the vowels into three groups:
Yin and
yang vowels could not occur in the same word, but could co-occur with the neutral vowel. The phonetic dimension underlying vowel harmony is disputed.
Ki-Moon Lee suggested that LMK vowel harmony was based on
vowel height. Some recent authors attribute it to
advanced and retracted tongue root states. Loans from
Middle Mongol in the 13th century show several puzzling correspondences, in particular between Middle Mongolian
ü and Korean
u. Based on these data and transcriptions in the
Jilin leishi, Ki-Moon Lee argued for a Korean Vowel Shift between the 13th and 15th centuries, consisting of
chain shifts involving five of these vowels: • > > > • > >
William Labov found that this proposed shift followed different principles to all the other chain shifts he surveyed. Lee's interpretation of both the Mongolian and
Jilin leishi materials has also been challenged by several authors. LMK also had two
glides,
y and
w : • A
y on-glide could precede four of the vowels, indicated in Hangul with modified letters:
ya ,
ye ,
ywo and
ywu . • A
w on-glide could precede
a or
e, written with a pair of vowel symbols:
wa and
we . • A
y off-glide could follow any of the pure vowels except
i or any of the six onglide-vowel combinations, and was marked by adding the letter
i . In modern Korean, the vowel-offglide sequences have become monophthongs. Early Hangul texts distinguish three pitch contours on each syllable: low (unmarked), high (marked with one dot) and rising (marked with two dots). The rising tone may have been longer in duration, and is believed to have arisen from a contraction of a pair of syllables with low and high tone. LMK texts do not show clear distinctions after the first high or rising tone in a word, suggesting that it was a
pitch-accent language rather than having a full
tone system. == Vocabulary ==