Four letters mark north, south, east and west. Eight more fill in the circle. Twelve vowels, like twelve notes – and a compass that points to the vowels of every language.
The four directions, in one box.
North (子) = ㆆ (sunset) = close
South (午) = ㆍ (sun) = open
East (卯) = ㅣ (tree) = front
West (酉) = ㅡ (ground) = back
1. Where we left off
In the last post we met King Sejong the musician. He read Yullyeo Sinseo, a book on tuning the twelve notes, with his scholars, and the music book Akhak gwebeom later drew those twelve notes on a circle, each one standing on one of the twelve earthly branches. The first note, Hwangjong, stands on 子: north, midnight, the winter solstice.
《악학궤범》(1493)의 원도 — 12지지 위에 놓인 12율, 子 자리에 황종.
We ended with a question: what if Sejong’s vowels were also a set of twelve, set on the same circle? The book’s answer is a picture. It calls it the vowel compass.
2. The vowel compass
책의 모음나침반 — 12지지 각 자리에 모음 하나씩. (일부 모음 옆의 연한 회색 글자는 ㅑ처럼 y가 붙은 꼴.)
Read it like a compass. Look first at the middle of each side, where one letter stands alone:
- Top – north – 子 – ㆆ. Winter. The color of the north is black; the book shades it gray so the letters can still be read.
- Bottom – south – 午 – ㆍ, the red dot. Summer, red.
- Left – east – 卯 – ㅣ, blue-green. Spring, wood.
- Right – west – 酉 – ㅡ, metallic white. Autumn, metal.
Notice one thing at once: east is on the left. On a road map east is on the right, but this compass is drawn the way a face is drawn in a phonetics book – looking to the left. The front of the mouth is on the left, so ㅣ, the front vowel, stands on the left. Keep that in mind; it is the reason the compass fits the IPA chart so well (section 4).
These four letters are the kings of the compass. The other eight vowels around them are mixtures of the kings, and we will come back to them in section 5. First, the kings.
3. The four kings in the mouth
Before they are directions on a compass, the four kings are places in the mouth:
책 그림 — 왼쪽을 보는 얼굴: 앞니의 ㅣ(초록), 혀뿌리의 ㅡ, 평평한 혀 위의 ㆆ(파랑), 성대의 ㆍ(빨간 점).
| Letter | Direction | Where it is | What it tells you |
|---|---|---|---|
| ㆍ (Heaven) | south, 午 | the vocal cords, deep in the throat – the only thing that makes the buzz of a vowel | open your jaw wider: open |
| ㆆ | north, 子 | the empty space above the tongue, when the tongue lies flat and tight | keep the tongue flat: close |
| ㅣ (Human) | east, 卯 | the will to speak: the resting tongue pushed forward, to the front teeth | front |
| ㅡ (Earth) | west, 酉 | the root of the tongue, lying flat at the back like the horizon | back |
The book also gives each king a picture from nature. In the drawing on the right below, ㆍ is the sun high in the summer sky, ㅣ is a tree – a stem standing up in spring – and ㅡ is the ground after the autumn harvest. ㆆ is the sun after sunset, gone below the line of the earth; it is also the jar in which seeds sleep through the winter.
책 그림 — 같은 모음들을 입 안(왼쪽)과 해 아래 들판(오른쪽)에 놓은 모습.
Say it once more: north ㆆ sunset, south ㆍ sun, east ㅣ tree, west ㅡ ground.
4. How to use the compass
A compass is only useful if you know how to walk with it. The book gives the instructions in four lines, next to this picture:
책 그림 — 가운데에서 출발해 화살표를 따라간다.
ㆆ is north. When it is added, move from the center toward close on the vowel chart.
ㅣ is east. When it is added, move from the center toward front.
ㅡ is west. When it is added, move from the center toward back.
ㆍ is south. When it is added, move from the center toward open.
The “vowel chart” here is the IPA vowel chart, the map every phonetics student learns: close vowels at the top, open vowels at the bottom, front vowels on the left, back vowels on the right. Now lay the compass over it. The book does exactly that:
책 그림 — IPA 모음사각도의 네 방위: 위 ㆆ(고), 아래 ㆍ(저), 왼쪽 ㅣ(전설), 오른쪽 ㅡ(후설).
The four kings land exactly on the four sides of the IPA chart – north on top, south at the bottom, east on the left, west on the right. That is why the compass has east on the left: it was drawn to fit the mouth, and the IPA chart is a map of the mouth.
So a 正音 vowel is a set of directions. You do not need to memorize where each one goes – just look at the letters inside it. The book shows this at a glance:
책 그림 — ㅣ가 든 모음은 전설모음, ㅗ·ㅜ가 든 모음은 원순모음, ㆆ가 든 모음은 평순 고모음, ㆍ가 든 모음은 저모음.
Try it with a few pairs from the chart below:
- Add ㆆ and go north: ㅡ [ɤ] becomes ᅙᅳ [ɯ]; ㅔ [e̞] becomes ᅙᅦ [e].
- Add ㆍ and go south: ㅏ [ɐ] becomes ᅟퟅ [ɑ]; ㅓ [ʌ] becomes ᅟᆟ [ɔ].
- Add ㅣ and go east: ㅜ [u] becomes ᅟᆛ [y]; ㅗ [o] becomes ᅟᆚ [ø].
Here is the whole IPA chart written in 正音, as the book gives it. Find ㅣ at the top left, ㅜ at the top right, and follow the directions:
![A table from the book, in Korean: the IPA vowel chart from front to back (columns) and from close to open (rows), each IPA symbol followed by its Jeongeum spelling in brackets, such as i [ㅣ], y, u [ㅜ], e, ø, ɤ [ㅡ], ɛ [ㅐ], œ [ㆉ], ʌ [ㅓ], ɐ [ㅏ] and ɑ.](https://i0.wp.com/hun-min.com/wp-content/uploads/2026/11/vowel-chart-book-p159.png?resize=660%2C350&ssl=1)
책의 IPA 모음표 — 세로줄은 전설부터 후설까지(평순/원순 구분), 가로줄은 고모음부터 저모음까지.
On the IPA chart: ㆆ (north) is the top, close. ㆍ (south) is the bottom, open. ㅣ (east) is the left, front. ㅡ (west) is the right, back.
5. The other eight vowels
Now go back to the compass in section 2 and look at the corners. The eight vowels there are mixtures of the kings. ㆍ mixed with ㅡ gives the round vowels ㅗ and ㅜ; ㆍ mixed with ㅣ gives ㅏ and ㅓ. Say any of these four with the tongue at ㅣ – a step east – and you get the last four: ㅐ, ㅔ, [ø] and [y]. That is all twelve. And because every one of them is built from the four kings, you can read every one of them with the same four directions.
(The book builds the circle step by step in three “days” and ties each vowel to a month of the year. That story is told in the Korean post II. 모음사각도 Day1, 2, 3.)
6. Remember the kings
Keep only the four kings in your head. Every other vowel is a walk from the center toward one or two of them:
North 子 ㆆ sunset → close
South 午 ㆍ sun → open
East 卯 ㅣ tree → front
West 酉 ㅡ ground → back
The IPA chart is a map that phoneticians drew in the last hundred years. Sejong’s scholars marked the same four directions in 1446 with four simple strokes, and set them on the same twelve-step circle that tuned the king’s bells.
7. Read more
This post is a short English version of ideas from the book 《正音으로 듣고쓰다》 (Listening and Writing with Jeongeum); all the pictures are from the book. The Korean originals go much further:
- II. 모음사각도 Day1, 2, 3 – the three days of the vowel compass (Korean)
- I. 12율려 (陽律陰呂在位圖說) – the twelve notes and the vowels (Korean)
- III. 方合 三合 六合 6해 6충 6파 – how the twelve vowels combine (Korean)
- 국제발음기호(IPA)와 正音(orthophon) – the IPA vowel chart in 正音 (Korean)