Tone letter

Tone letters are special symbols that show the different ways a sound can be said in a language. These ways, called tones, can change the meaning of a word.

Many languages, especially in parts of Asia and Africa, use tones. Tone letters help people write words so others know exactly how to say them.

For example, in some languages, saying a word with a high tone might mean one thing, while saying it with a low tone means something else. Tone letters help show these differences in writing.

These symbols are used in books, dictionaries, and language studies to make sure everyone understands the right meaning of each word.

Chao tone letters (IPA)

A special set of symbols for showing tones in speech was created by Yuen Ren Chao in the 1920s. These symbols add musical notes to the International Phonetic Alphabet. They help show small changes in pitch that were hard to see before. These symbols can show up to five levels of pitch: very high, high, middle, low, and very low.

These tone letters are usually placed at the end of a word. For example, in Standard Mandarin, they show the four different tones of a syllable. In some languages, single tone letters show simple tones, while two letters show more complex changes in pitch. These symbols can also be placed before a syllable to show stress or changes in pitch before the word starts.

Other ways to show tone exist, like using special marks above or below letters. For example, the four tones in Mandarin can also be written with these marks.

Reversed Chao tone letters

Reversed tone letters show how tones change when words are put together. They help show the underlying tone and the changed tone.

Reversed tone letters were added to the International Phonetic Alphabet in 1989.

Capital-letter abbreviations

Sometimes, we use big letters to show the tones in a language. For example, H means "high," M means "middle," and L means "low." If the tone goes down, we might write HM or HL. If it goes up, we might write LM or MH. These letters can stand alone or be used with other letters to describe sounds.

Numerical values

Tone letters are sometimes written as numbers, especially in languages from Asia and Mesoamerica that have different tones. Before special computer fonts became common around the year 2000, using numbers was a practical way to show tone changes. For example, the four tones in Mandarin Chinese can be written as "ma55", "ma35", "ma214", and "ma51".

But these number systems can be confusing. In Chinese, the lowest pitch is called 1 and the highest is called 5. In some African languages, it’s the opposite—the lowest pitch is 5 and the highest is 1. In other places, like some Mesoamerican languages, the highest pitch might be 1, but the lowest pitch depends on how many different tones the language has. This can cause misunderstandings if someone used to one system sees numbers from another system. Tone letters avoid this confusion because they clearly show pitch changes like musical notes.

Division of tone space

The International Phonetic Association suggests using tone letters to show the different sounds in a language's tones. For example, if a language has one falling tone, it is written as /˥˩/.

There are three ways to study tones: linear, exponential, and ways that are specific to a language. In a linear way, tones are matched to the basic sound pitch (f₀). This is done by taking the tone with the lowest pitch and the tone with the highest pitch, and splitting the space between them into four equal parts. Tone letters are picked based on how the pitch changes. This linear way is organized, but it doesn’t always match the start and end of each tone with the planned levels. An older idea by Chao used an exponential way, suggesting five tone levels spaced two semitones apart.

IPA tone letters in Unicode

See also: Spacing Modifier Letters and Modifier Tone Letters

In Unicode, special letters are used to show tones in some languages. These are called IPA tone letters.

They include:

Standard staved tone letters:

• U+02E5 ˥ MODIFIER LETTER EXTRA-HIGH TONE BAR
• U+02E6 ˦ MODIFIER LETTER HIGH TONE BAR
• U+02E7 ˧ MODIFIER LETTER MID TONE BAR
• U+02E8 ˨ MODIFIER LETTER LOW TONE BAR
• U+02E9 ˩ MODIFIER LETTER EXTRA-LOW TONE BAR

Reversed tone letters:

• U+A712 ꜒ MODIFIER LETTER EXTRA-HIGH LEFT-STEM TONE BAR
• U+A713 ꜓ MODIFIER LETTER HIGH LEFT-STEM TONE BAR
• U+A714 ꜔ MODIFIER LETTER MID LEFT-STEM TONE BAR
• U+A715 ꜕ MODIFIER LETTER LOW LEFT-STEM TONE BAR
• U+A716 ꜖ MODIFIER LETTER EXTRA-LOW LEFT-STEM TONE BAR

These can be combined for different tones, and special fonts will connect them correctly.

There are also dotted tone letters and several other symbols that can be used instead of the main tone letters, depending on the font. These include marks like the macron (ˉ), acute accent (ˊ), and grave accent (ˋ), among others.

Non-IPA systems

Although the phrase "tone letter" usually refers to the Chao system in the context of the IPA, there are also writing systems with letters assigned to individual tones, which may also be called tone letters.

UPA

The Uralic Phonetic Alphabet has marks that look like half brackets to show the start and end of high and low tones: mid tone  ˹high tone˺  ˻low tone˼. It also uses ꜠ for high-pitch stress and ꜡ for low-pitch stress.

Chinese

Main article: Four tones (Middle Chinese)

Besides systems that show meaning-based sounds, Chinese is often written with marks placed at the side of a word to show its tone group. There are marks for four to eight historic tone groups.

When the difference between yin and yang tones is not needed, the yin tone marks are used.

See also bopomofo.

Zhuang

In some systems, tone numbers are used in writing and are technically letters even though they are still called "numbers". In the 1957 Chinese writing system for Zhuang, the numbers were changed to look different from regular numbers. Two letters from the Cyrillic alphabet, ⟨з⟩ and ⟨ч⟩, replaced the numbers ⟨3⟩ and ⟨4⟩. In 1982, these were changed to Latin letters, with ⟨h⟩ now used for both a consonant sound and a mid tone.

Hmong and Unified Miao

The Hmong Romanized Popular Alphabet created in the early 1950s uses Latin letters for tones. Two of these "tones" are better called register, since tone is not what makes them different. Some letters are used for both consonants and tones.

A unified Miao alphabet used in China uses a different system:

Chatino

In Highland Chatino, special superscript letters from A to L show groups of similar tones across dialects. The way these tones are said can change between dialects, and some tones may sound the same in one dialect but different in another, due to tone splits and merging. Superscript M and S are used for tone sandhi.

Chinantec

Different ways of writing Chinantec tones have been created. Linguists usually use superscript numbers or IPA.

Ozumacín Chinantec uses special marks:

⟨ˈ, ˉ, ˊ, ˋ, ꜗ, ꜘ, ꜙ, ꜚ⟩.

Korean

In hangul and sometimes when writing it using Latin letters, ⟨〮⟩ and ⟨〯⟩ are used for historic vowel length and pitch accent.

Lahu and Akha

The related languages Lahu and Akha use special spacing marks that appear at the end of a syllable. Mid tone is not marked.

Ethiopic

Ethiopic tone marks are small symbols printed above each letter, similar to ruby text. They include:

᎐ yizet

᎑ deret

᎒ rikrik

᎓ short rikrik

᎔ difat

᎕ kenat

᎖ chiret

᎗ hidet

᎘ deret-hidet

᎙ kurt