សូរ (​ភាសាសាស្ត្រ​)

សូវ គឺ​ជា​ការប្រើប្រាស់​នៃ​ការលើកដាក់សំឡេង​ក្នុង​ភាសា​មួយ​ដើម្បី​ប្តូរ​ន័យ​ពាក្យ​ឬ​វេយ្យករណ៍​។   គ្រប់​ភាសា​មាត់​ប្រើប្រាស់​ការលើកដាក់សំឡេង​ដើម្បី​បង្ហាញ​ព័ត៌មាន​ខាង​អារម្មណ៍​និង​ភាសាសាស្ត្រ ហើយបង្ហាញ​ការសង្កត់​ភាពផ្ទុយគ្នា និង​លក្ខណៈ​ដទៃ​ក៏​ហៅ​ថា តានា ប៉ុន្តែ​មិន​មែន​គ្រប់​ភាសា ប្រើ​តានា​នេះ​ប្តូរ​នៃ​ពាក្យ​ឬ​ការផ្លាស់ប្ដូរ​របស់ ដូច​ជា​ព្យញ្ជនៈ​និង​ស្រៈ​ទេ​។ មូលសទ្ទ​បែប​នេះ​ក៏​ហៅ​ថា មូលតានា (​ជា​ភាសាបារាំង​៖ tonèmes [tɔ'nɛm])​ នៅ​ដែល​ មូលតានា មួយ​ខុស​ពី​មូលសទ្ទ​ដូចគ្នា​តាម​សទ្ទានុក្រម​ និយាយ​អញ្ចឹង មាន​សម្លេង​ខុស​ពី​មូលតានា​ដទៃ គ្រាន់តែ​ដោយ​ការលើកដាក់សំឡេង​នៃ​ស្រៈ​។ ភាសា​សូរសំឡេង មាន​ច្រើន​នៅ​ទ្វីប​អាហ្វ្រិក ទ្វីប​អាស៊ី​ខាង​កើត ហើយ​​ប្រទេសម៉ិចស៊ិក​និង​អាមេរិក​កណ្តាល  ប៉ុន្តែ​មិន​សូវ​មាន​នៅ​តំបន់ដទៃ ក្នុង​ទ្វីប​អាស៊ី​និង​ទ្វីប​អឺរ៉ុប។ យ៉ាង​ធំ ភាសា ៧០ ភាគ​រយ អាចជា​ភាសា​សូវ​សំឡេង​។​

In many tonal African languages, such as most Bantu languages, tones are distinguished by their pitch level relative to each other, known as a register tone system.  In multisyllable words, a single tone may be carried by the entire word, rather than a different tone on each syllable. Often grammatical information, such as past versus present, "I" versus "you", or positive versus negative, is conveyed solely by tone.

In the most widely-spoken tonal language, Mandarin Chinese, tones are distinguished by their distinctive shape, known as contour, with each tone having a different internal pattern of rising and falling pitch. Words are often monosyllabic, and many words are differentiated solely by tone; in a multisyllabic word each syllable often carries its own tone. Unlike in Bantu systems, tone plays little role in modern Chinese grammar, though the tones descend from features in Old Chinese that did have morphological significance (e.g. changing a verb to a noun or vice-versa).

Contour systems are typical of languages of the Mainland Southeast Asia linguistic area, including Tai–Kadai, Vietic and Sino-Tibetan languages, while the Afroasiatic, Nilo-Saharan, Khoi-San and Niger-Congo languages of Africa are dominated by register systems.  Some languages combine both systems, such as Cantonese, which produces three varieties of contour tone at three different pitch levels, or the Omotic (Afroasiatic) language Bench, which employs five level tones and one or two rising tones across levels.

Many languages use tone in a more limited way. Somali, for example, may only have one high tone per word. In Japanese, fewer than half of the words have drop in pitch; words contrast according to which syllable this drop follows. Such minimal systems are sometimes called pitch accent, since they are reminiscent of stress accent languages which typically allow one principal stressed syllable per word. However, there is debate over the definition of pitch accent, and whether a coherent definition is even possible.

Tonal languages
Most languages of sub-Saharan Africa are members of the Niger-Congo family which is predominately tonal, notably excepting Swahili (in the Southeast), most languages spoken in the Senegambia (among them Wolof, Serer and Cangin languages), Koyra Chiini and Fulani. The Afroasiatic languages of Northeastern sub-Saharan Africa include both tonal (Chadic, Omotic, and to some extent Cushitic) and nontonal (Semitic, Berber, and Egyptian) branches.

There are numerous tonal languages in East Asia and South East Asia.  Most Sino-Tibetan languages including all the Chinese languages (though some such as Shanghainese are only marginally tonal), Lhasa Tibetan and Burmese are tonal, as are Austroasiatic languages such as, Vietnamese, Tai-Kadai languages including Thai, and Lao, and Austronesian languages Cemuhi. However, some members of these families are also nontonal including Amdo Tibetan, Khmer and Malay.  Other languages represented in the region, such as Mongolian, Uyghur and Japanese belong to language families that do not contain any tonality as defined here.

A few languages outside these major groups have tonality, including Lahnda, Punjabi and Ancient Greek, which are Indo-European languages.  Although the Austronesian language family has some tonal members, no tonal languages have been discovered in Australia.

A large number of North, South and Central American languages are tonal, including many of the Athabaskan languages of Alaska and the American Southwest (including Navajo), and the Oto-Manguean languages of Mexico. Among the Mayan languages, which are mostly non-tonal, Yucatec (with the largest number of speakers), Uspantek, and one dialect of Tzotzil have developed tone systems.  However, although tone systems have been recorded for many American languages, little theoretical work has been completed for the characterization of their tone systems.  In different cases, Central American tone languages have been found to possess tone systems similar to both Asian and African tone languages.

Languages that are tonal include:
Some of the Sino-Tibetan languages. Most forms of Chinese, some Tibetan languages, including the standard languages of Lhasa and Bhutan and Burmese.
In the Austro-Asiatic family, Vietnamese and other members of the Vietic family are strongly tonal. Other branches of this family, such as Mon, Khmer, and the Munda languages, are entirely non-tonal.
The entire Tai-Kadai family, spoken mainly in China, Vietnam, Thailand, and Laos, and including Thai and Lao is tonal.
The entire Hmong–Mien family is tonal.
Many Afroasiatic languages in the Chadic, Cushitic and Omotic families have register tone systems, including Hausa. Omotic languages are an exception in this family in having both contour and register tones; most have only two to three register tones, like Somali.
The vast majority of Niger–Congo languages, such as Ewe, Igbo, Lingala, Maninka, Yoruba, and the Zulu, have register tone systems. The Kru languages have contour tones. Notable non-tonal Niger–Congo languages are Swahili, Fula, and Wolof.
Most Nilo-Saharan languages including Dinka and Luo have register tone systems.
All Khoisan languages in southern Africa have contour tone systems; some languages like Sandawe have mixed tone systems like that of Cantonese.
Slightly more than half of the Athabaskan languages, such as Navajo, have register tone systems (languages in California, Oregon and a few in Alaska excluded). The Athabaskan tone languages fall into two "mirror image" groups. That is, a word which has a high tone in one language will have a cognate with a low tone in another, and vice versa.
Iroquoian languages like Mohawk have register tone.
All Oto-Manguean languages are tonal. Most have register tone, though some have contour tones as well.  In some cases, as with Mixtec, tone system variations between dialects are sufficiently great to cause mutual unintelligibility.
Many Papuan languages of New Guinea like Siane possess register tone systems.
Some Indo-European languages as well as others possess what is termed pitch accent, where changes in pitch (as opposed to amplitude) mark the stressed syllable in an utterance; these are not always considered to be cases of tone language.
Some European-based creole languages, such as Saramaccan and Papiamentu, have tone from their African substratum languages.

In some cases it is difficult to determine whether a language is tonal. For example, the Ket language has been described as having up to eight tones by some investigators, as having four tones by others, but by some as having no tone at all. In cases such as these, the classification of a language as tonal may depend on the researcher's interpretation of what tone is. For instance, the Burmese language has phonetic tone, but each of its three tones is accompanied by a distinctive phonation (creaky, murmured or plain vowels). It could be argued either that the tone is incidental to the phonation, in which case Burmese would not be phonemically tonal, or that the phonation is incidental to the tone, in which case it would be considered tonal. Something similar appears to be the case with Ket.

The 19th-century constructed language Solresol, attempts to convey information using only tone.

Mechanics
Most languages use pitch as intonation to convey prosody and pragmatics, but this does not make them tonal languages. In tonal languages, each syllable has an inherent pitch contour, and thus minimal pairs (or larger minimal sets) exist between syllables with the same segmental features but different tones.

Here is a minimal tone set from Mandarin Chinese, which has five tones, here transcribed by diacritics over the vowels:

 A high level tone: /á/ (pinyin ⟨ā⟩)
 A tone starting with mid pitch and rising to a high pitch: /ǎ/ (pinyin ⟨á⟩)
 A low tone with a slight fall (if there is no following syllable, it may start with a dip then rise to a high pitch): /à/ (pinyin ⟨ǎ⟩)
 A short, sharply falling tone, starting high and falling to the bottom of the speaker's vocal range: /â/ (pinyin ⟨à⟩)
 A very short, neutral tone, sometimes indicated by a dot (·) in Pinyin, has no specific contour; its pitch depends on the tones of the preceding and following syllables. Mandarin speakers refer to this tone as the "light tone" (), also called the "fifth tone", "zeroth tone", or "neutral tone". This tone occurs only on unstressed syllables. Its occurrence on single syllable words is marginal, only with a small number of grammatical particles. There is a strong tendency in modern Mandarin for the second syllable of disyllabic words to be pronounced with a light tone. 

These tones combine with a syllable such as "ma" to produce different words. A minimal set based on "ma" are, in pinyin transcription,
mā(媽/妈) "mum/mom"
má(麻/麻) "hemp"
mǎ(馬/马) "horse"
mà(罵/骂) "scold"
ma(嗎/吗) (an interrogative particle)

These may be combined into the rather contrived sentence,

/
Pinyin: māma mà mǎ de má ma?
IPA /má ma mâ ma᷉ tɤ mǎ ma/
English: "Is mom scolding the horse's hemp?"

A well-known tongue-twister in the Thai language is:

IPA: 
"Does new silk burn?"

Vietnamese has its version:

IPA: /bʌ̌j naj bʌj bʌ̂j bʌ᷉j bʌ̌ˀj bʌ̂ˀj/
"All along you've set up the seven traps incorrectly!"

Tone is most frequently manifested on vowels, but in most tonal languages where voiced syllabic consonants occur they will bear tone as well. This is especially common with syllabic nasals, for example in many Bantu and Kru languages, but also occurs in Serbo-Croatian.

Tones can interact in complex ways through a process known as tone sandhi.

Register tones and contour tones
ប្រព័ន្ធសម្លេងធ្លាក់ចូលទៅក្នុងលំនាំធំទូលាយពីរ យោងទៅតាមថាតើមានសម្លេងវណ្ឌវង្កដែរឬទេ។

Most Chinese languages use contour tone systems, where the distinguishing feature of the tones are their shifts in pitch (that is, the pitch is a contour), such as rising, falling, dipping, or level. Most Bantu languages, on the other hand, have non-contour tone (or register tone) systems where the distinguishing feature is the relative difference between the pitches, such as high, mid, or low, rather than their shapes. In such systems there is a default tone, usually low in a two-tone system or mid in a three-tone system, that is more common and less salient than other tones. There are also languages that combine relative-pitch and contour tones, such as many Kru languages, where nouns are distinguished by contour tones and verbs by pitch. Others, such as Yoruba, have phonetic contours, but these can easily be analysed as sequences of single-pitch tones, with for example sequences of high–low  becoming falling , and sequences of low–high  becoming rising .

Falling tones tend to fall further than rising tones rise; high–low tones are common, whereas low–high tones are quite rare. A language with contour tones will also generally have as many or more falling tones than rising tones. However, exceptions are not unheard of; Mpi, for example, has three level and three rising tones, but no falling tones.

Lexical tones more complex than dipping (falling–rising) or peaking (rising–falling) are quite rare, perhaps nonexistent, though prosody may produce such effects. However, the Old Xiang dialect of Qiyang is reported to have two "double contour" lexical tones, high and low fall–rise–fall, or perhaps high falling – low falling and low falling – high falling:  and  (4232 and 2142).

Register phonation
In a number of East Asian languages, tonal differences are closely intertwined with phonation differences. In Vietnamese, for example, the ngã and sắc tones are both high-rising but the former is distinguished by having a glottal stop in the middle. Similarly, the nặng and huyền tones are both low-falling, but the nặng tone is shorter and pronounced with creaky voice at the end, while the huyền tone is longer and often has breathy voice. In some languages, such as Burmese, pitch and phonation are so closely intertwined that the two are combined in a single phonological system, where neither can be considered without the other. Confusingly, such systems are termed register, which is unrelated to "register tone" as described above.

Tone terracing and tone sandhi

Tone terracing

Tones are realized as pitch only in a relative sense. 'High tone' and 'low tone' are only meaningful relative to the speaker's vocal range and in comparing one syllable to the next, rather than as a contrast of absolute pitch such as one finds in music. As a result, when one combines tone with sentence prosody, the absolute pitch of a high tone at the end of a prosodic unit may be lower than that of a low tone at the beginning of the unit, because of the universal tendency (in both tonal and non-tonal languages) for pitch to decrease with time in a process called downdrift.

Tones may affect each other just as consonants and vowels do. In many register-tone languages, low tones may cause a downstep in following high or mid tones; the effect is such that even while the low tones remain at the lower end of the speaker's vocal range (which is itself descending due to downdrift), the high tones drop incrementally like steps in a stairway or terraced rice fields, until finally the tones merge and the system has to be reset. This effect is called tone terracing.

Sometimes a tone may remain as the sole realization of a grammatical particle after the original consonant and vowel disappear, so it can only be heard by its effect on other tones. It may cause downstep, or it may combine with other tones to form contours. These are called floating tones.

Tone sandhi

In many contour-tone languages, one tone may affect the shape of an adjacent tone. The affected tone may become something new, a tone that only occurs in such situations, or it may be changed into a different existing tone. This is called tone sandhi. In Mandarin Chinese, for example, a dipping tone between two other tones is reduced to a simple low tone, which otherwise does not occur in Mandarin, whereas if two dipping tones occur in a row, the first becomes a rising tone, indistinguishable from other rising tones in the language. For example, the words 很  'very' and 好  'good' produce the phrase 很好  'very good'.

Word tones and syllable tones
Another difference between tonal languages is whether the tones apply independently to each syllable or to the word as a whole. In Cantonese, Thai, and to some extent the Kru languages, each syllable may have a tone, whereas in Shanghainese, the Scandinavian languages, and many Bantu languages, the contour of each tone operates at the word level. That is, a trisyllabic word in a three-tone syllable-tone language has many more tonal possibilities (3 × 3 × 3 = 27) than a monosyllabic word (3), but there is no such difference in a word-tone language. For example, Shanghainese has two contrastive tones no matter how many syllables are in a word. Many languages described as having pitch accent are word-tone languages.

Tone sandhi is an intermediate situation, as tones are carried by individual syllables, but affect each other so that they are not independent of each other. For example, a number of Mandarin suffixes and grammatical particles have what is called (when describing Mandarin) a "neutral" tone, which has no independent existence. If a syllable with a neutral tone is added to a syllable with a full tone, the pitch contour of the resulting word is entirely determined by that other syllable:

After high level and high rising tones, the neutral syllable has an independent pitch that looks like a mid-register tonethe default tone in most register-tone languages. However, after a falling tone it takes on a low pitch; the contour tone remains on the first syllable, but the pitch of the second syllable matches where the contour leaves off. And after a low-dipping tone, the contour spreads to the second syllable: the contour remains the same () whether the word has one syllable or two. In other words, the tone is now the property of the word, not the syllable. Shanghainese has taken this pattern to its extreme, as the pitches of all syllables are determined by the tone before them, so that only the tone of the initial syllable of a word is distinctive.

Tonal polarity
Languages with simple tone systems or pitch accent may have one or two syllables specified for tone, with the rest of the word taking a default tone. Such languages differ in which tone is marked and which is the default. In Navajo, for example, syllables have a low tone by default, while marked syllables have high tone. In the related language Sekani, however, the default is high tone, and marked syllables have low tone. There are parallels with stress: English stressed syllables have a higher pitch than unstressed syllables, whereas in Russian, stressed syllables have a lower pitch.

Uses of tone
In East Asia, tone is typically lexical. This is characteristic of heavily tonal languages such as Chinese, Vietnamese, Thai, and Hmong. That is, tone is used to distinguish words which would otherwise be homonyms, rather than in the grammar, though some Yue Chinese dialects have minimal grammatical use of tone. (In Old Chinese, tones may have grammatical functions.) However, in many African languages, especially in the Niger–Congo family, tone is crucial to the grammar, with relatively little lexical use. In the Kru languages, a combination of these patterns is found: nouns tend to have complex tone systems reminiscent of East Asia, but are not much affected by grammatical inflections, whereas verbs tend to have simple tone systems of the type more typical of Africa, which are inflected to indicate tense and mood, person, and polarity, so that tone may be the only distinguishing feature between 'you went' and 'I won't go'. In colloquial Yoruba, especially when spoken quickly, vowels may assimilate to each other, and consonants elide, so that much of the lexical and grammatical information is carried by tone. In languages of West Africa such as Yoruba, people may even communicate with so-called "talking drums", which are modulated to imitate the tones of the language, or by whistling the tones of speech.

Tone as a linguistic feature may be less binary than it is typically conceived to be; the first image at right shows the distribution of all languages possessing more than two tones ('complex' tone), regardless of whether they are register or contour (or mixed) systems.

Note that tonal languages are not distributed evenly across the same range as non-tonal languages.  Instead, the majority of tone languages belong to the Niger-Congo, Sino-Tibetan and Austroasiatic groups, which are then composed by a large majority of tone languages and dominate a single region. Only in limited locations—South Africa, New Guinea, Mexico, Brazil and a few others do tone languages seem to occur as individual members or small clusters within a non-tone dominated area.  In some locations, like Central America, this may represent no more than an incidental effect of which languages were included when examining distribution; for groups like Khoi-San in Southern Africa and Papuan languages, whole families of languages possess tonality, but simply have relatively few members, while for some North American tone languages multiple independent origins are suspected.

If generally considering only complex-tone vs. no-tone it might be concluded that tone is almost always an ancient feature within a language family that is highly conserved among members.  However, when considered in addition to 'simple' tone systems that include only two tones, tone as a whole appears to be more labile, appearing several times within Indo-European, several times in American languages, and several times in Papuan families.  This may indicate that rather than a trait unique to some language families, tone is a latent feature of most language families that may more easily arise and disappear as languages change over time.

Phonetic notation

There are three main approaches to notating tones in phonetic descriptions of a language.
The easiest from a typological perspective is a numbering system, with the pitch levels assigned numerals, and each tone transcribed as a numeral or sequence of numerals. Such systems tend to be idiosyncratic, for example with high tone being assigned the numeral 1, 3, or 5, and so have not been adopted for the International Phonetic Alphabet.
Also simple for simple tone systems is a series of diacritics, such as ⟨ó⟩ for high tone and ⟨ò⟩ for low tone. This has been adopted by the IPA, but is not easy to adapt to complex contour tone systems (see under Chinese below for one work-around). The five IPA diacritics for level tones are . These may be combined to form contour tones, , though font support is sparse. Sometimes a non-IPA vertical diacritic for a second, higher, mid tone is seen, , so that in a language with four (or six) level tones, they may be transcribed .
The most flexible system is that of tone letters, which are iconic schematics of the pitch trace of the tone in question. They are most commonly used for complex contour systems, as in Liberia and southern China.

អាហ្រ្វិក
In African linguistics (as well as in many African orthographies), usually a set of accent marks is used to mark tone. The most common phonetic set (which is also included in the International Phonetic Alphabet) is found below:

Several variations are found. In many three-tone languages, it is common to mark High and Low tone as indicated above, but to omit marking of the Mid tone, e.g., má (High), ma (Mid), mà (Low). Similarly, in some two-tone languages, only one tone is marked explicitly.

With more complex tonal systems, such as in the Kru and Omotic languages, it is usual to indicate tone with numbers, with 1 for HIGH and 4 or 5 for LOW in Kru, but 1 for LOW and 5 for HIGH in Omotic. Contour tones are then indicated 14, 21, etc.

អាស៊ី
In the Chinese tradition, numerals are assigned to various tones (see Tone number). For instance, Standard Mandarin, the official language of China has four lexically contrastive tones, and the numerals 1, 2, 3, and 4 are assigned to four tones. Syllables can sometimes be toneless and are described as having a neutral tone, typically indicated by omitting tone markings. Chinese dialects are traditionally described in terms of four tonal categories ping 'level', shang 'rising', qu 'exiting', ru 'entering', based on the traditional analysis of Middle Chinese (see Four tones); note that these are not at all the same as the four tones of modern standard Mandarin. Depending on the dialect, each of these categories may then be divided into two tones, typically called yin and yang. Syllables carrying the ru tones are closed by voiceless stops in all Chinese dialects, so that ru is not a tonal category in the sense used by Western linguistics, but rather a category of syllable structures. Chinese phonologists perceived these checked syllables as having concomitant short tones, justifying them as a tonal category. During the period of Middle Chinese, when the tonal categories were established, the shang and qu tones also had characteristic final obstruents with concomitant tonic differences, whereas syllables bearing the ping tone ended in a simple sonorant. An alternate to using the Chinese category names is to assign to each category a numeral ranging from 1–8, or sometimes higher for some Southern Chinese languages with additional tone splits. It should be noted that syllables belonging to the same tone category differ drastically in actual phonetic tone across the Chinese languages even amongst sub-dialects of the same language/dialect group. For example, the yin ping tone is a high level tone in Beijing Mandarin, but a low level tone in Tianjin Mandarin.

More iconic systems use tone numbers, or an equivalent set of graphic pictograms known as 'Chao tone letters'. These divide the pitch into five levels, with the lowest being assigned the value 1, and the highest the value 5. (This is the opposite of equivalent systems in Africa and the Americas.) The variation in pitch of a tone contour is notated as a string of two or three numbers. For instance, the four Mandarin tones are transcribed as follows (note that the tone letters will not display properly unless you have a compatible font installed):

A mid-level tone would be indicated by /33/, a low level tone /11/, etc. The doubling of the number is commonly used with level tones to distinguish them from tone numbers; tone 3 in Mandarin, for example, is not mid /3/. However, this is not necessary with tone letters, so /33/ = simple .

IPA diacritic notation is also sometimes seen for Chinese. One reason it is not more widespread is that only two contour tones, rising  and falling , are widely supported by IPA fonts, while several Chinese languages have more than one rising or falling tone. One common work-around is to retain standard IPA  and  for high-rising (/35/) and high-falling (/53/) tones, and to use the subscript diacritics  and  for low-rising (/13/) and low-falling (/31/) tones.

The Thai language has five tones: high, mid, low, rising and falling. The Thai written script is an alphasyllabary which specifies the tone unambiguously. Tone is indicated by an interaction of the initial consonant of a syllable, the vowel, the final consonant (if present), and sometimes a tone mark. A particular tone mark may denote different tones depending on the initial consonant.

Vietnamese uses the Latin alphabet, and the 6 tones are marked by diacritics above or below a certain vowel of each syllable. In many words that end in diphthongs, however, exactly which vowel is marked depends on the writer's style. Notation for Vietnamese tones are as follows:

The Latin-based Hmong and Iu Mien alphabets use full letters for tones. In Hmong, one of the eight tones (the  tone) is left unwritten, while the other seven are indicated by the letters b, m, d, j, v, s, g at the end of the syllable. Since Hmong has no phonemic syllable-final consonants, there is no ambiguity. This system enables Hmong speakers to type their language with an ordinary Latin-letter keyboard without having to resort to diacritics. In the Iu Mien, the letters v, c, h, x, z indicate tones but, unlike Hmong, it also has final consonants written before the tone.

អាមេរិក​ខាង​ជើង
Several North American languages have tone, one of which is Cherokee, an Iroquoian language. Oklahoma Cherokee has six tones (1 low, 2 medium, 3 high, 4 very high, 5 rising and 6 falling).

In Mesoamericanist linguistics, /1/ stands for high tone and /5/ stands for low tone, except in Oto-Manguean languages, where /1/ may be low tone and /3/ high tone. It is also common to see acute accents for high tone and grave accents for low tone and combinations of these for contour tones. Several popular orthographies use ⟨j⟩ or ⟨h⟩ after a vowel to indicate low tone
Southern Athabascan languages that include the Navajo and Apache languages are tonal, and are analyzed as having 2 tones, high and low. One variety of Hopi has developed tone, as has the Cheyenne language.

The Mesoamerican language stock called Oto-Manguean is famously tonal and is the largest language family in Mesoamerica, containing languages including Zapotec, Mixtec, and Otomí, some of which have as many as five register tones (Trique, Usila Chinantec) and others only two (Matlatzinca and Chichimeca Jonaz). Other languages in Mesoamerica that have tones are Huichol, Yukatek Maya, the Tzotzil of San Bartolo, Uspanteko, and one variety of Huave.

អា​មេ​រិ​ច​ខាងត្បូង

A number of languages of South America are tonal. For example, various analyses of the Pirahã language describe either two or three tones. The Ticuna language isolate is exceptional for having five register tones (the only other languages in America to have such a system are Trique and Usila, mentioned above).

អឺរ៉ុប
Both Swedish and Norwegian have simple word tone systems, often called pitch accent, that only appears in words of two or more syllables. Each word has a mandatory tone, which varies by dialect. Words whose pronunciation differs only in tone are frequently morphologically unrelated, and may be spelled differently, as in the Norwegian 'cider' ("sweet cider") and 'sider' ("pages"). The two word tones are called toneme 1 and toneme 2 in Norway and acute accent and grave accent in Sweden.

In Limburgish tones can also occur in words of one syllable: dáág (one day), dààg (several days).

Practical orthographies
In practical alphabetic orthographies, a number of approaches are used. Diacritics are common, as in pinyin, though these tend to be omitted. Thai uses a combination of redundant consonants and diacritics. Tone letters may also be used, for example in Hmong RPA and several minority languages in China. Or tone may simply be ignored. This is possible even for highly tonal languages: for example, the Chinese navy has successfully used toneless pinyin in government telegraph communications for decades, and likewise Chinese reporters abroad may file their stories in toneless pinyin. Dungan, a variety of Mandarin spoken in Central Asia, has, since 1927, been written in orthographies that do not indicate tone. Ndjuka, where tone is less important, ignores tone except for a negative marker. However, the reverse is also true: in the Congo, there have been complaints from readers that newspapers written in orthographies without tone marking are insufficiently legible.

Number of tones
Languages may distinguish up to five levels of pitch, though the Chori language of Nigeria is described as distinguishing six surface tone registers. Since tone contours may involve up to two shifts in pitch, there are theoretically 5 x 5 x 5 = 125 distinct tones for a language with five registers. However, the most that are actually used in a language is a tenth of that number.

Several Kam–Sui languages of southern China have nine contrastive tones, including contour tones. For example, the Kam language has 9 tones: 3 more-or-less fixed tones (high, mid and low); 4 unidirectional tones (high and low rising, high and low falling); and 2 bidirectional tones (dipping and peaking). This assumes that checked syllables are not counted as having additional tones, as they traditionally are in China: For example, in the traditional reckoning, the Kam language has 15 tones, but 6 occur only in syllables closed with /p/, /t/ or /k/ while the other 9 occur in syllables not ending in one of these sounds. Preliminary work on the Wobe language of Liberia and Côte d'Ivoire, and the Chatino languages of southern Mexico suggests that some dialects may distinguish as many as fourteen tones, but many linguists have expressed doubts, believing that many of these will turn out to be sequences of tones or prosodic effects.

Origin 

André-Georges Haudricourt established that Vietnamese tone originated in earlier consonantal contrasts, and suggested similar mechanisms for Chinese. It is now widely held that Old Chinese did not have phonemically contrastive tone. The historical origin of tone is called tonogenesis, a term coined by James Matisoff. Tone is frequently an areal rather than a genealogical feature. That is, a language may acquire tones through bilingualism if influential neighboring languages are tonal, or if speakers of a tonal language shift to the language in question, and bring their tones with them. In other cases, tone may arise spontaneously, and surprisingly quickly: the dialect of Cherokee in Oklahoma has tone, but the dialect in North Carolina does not, although they were only separated in 1838.

Very often, tone arises as an effect of the loss or merger of consonants. (Such trace effects of disappeared tones or other sounds have been nicknamed Cheshirisation, after the lingering smile of the disappearing Cheshire Cat in Alice in Wonderland.) In a non-tonal language, voiced consonants commonly cause following vowels to be pronounced at a lower pitch than other consonants do. This is usually a minor phonetic detail of voicing. However, if consonant voicing is subsequently lost, that incidental pitch difference may be left over to carry the distinction that the voicing had carried, and thus becomes meaningful (phonemic). This is seen historically in Panjabi: the Panjabi murmured (voiced aspirate) consonants have disappeared, and left tone in their wake. If the murmured consonant was at the beginning of a word, it left behind a low tone; if at the end, a high tone. If there was no such consonant, the pitch was unaffected; however, the unaffected words are limited in pitch so as not to interfere with the low and high tones, and so has become a tone of its own: mid tone. The historical connection is so regular that Panjabi is still written as if it had murmured consonants, and tone is not marked: the written consonants tell the reader which tone to use.

Similarly, final fricatives or other consonants may phonetically affect the pitch of preceding vowels, and if they then weaken to /h/ and finally disappear completely, the difference in pitch, now a true difference in tone, carries on in their stead. This was the case with the Chinese languages: Two of the three tones of Middle Chinese, the "rising" and "departing" tones, arose as the Old Chinese final consonants  and  disappeared, while syllables that ended with neither of these consonants were interpreted as carrying the third tone, "even". Most dialects descending from Middle Chinese were further affected by a tone split, where each tone divided in two depending on whether the initial consonant was voiced: Vowels following a voiced consonant (depressor consonant) acquired a lower tone as the voicing lost its distinctiveness.

The same changes affected many other languages in the same area, and at around the same time (AD 1000–1500). The tone split, for example, also occurred in Thai, Vietnamese, and the Lhasa dialect of Tibetan.

In general, voiced initial consonants lead to low tones, while vowels after aspirated consonants acquire a high tone. When final consonants are lost, a glottal stop tends to leave a preceding vowel with a high or rising tone (although glottalized vowels tend to be low tone, so if the glottal stop causes vowel glottalization, that will tend to leave behind a low vowel), whereas a final fricative tends to leave a preceding vowel with a low or falling tone. Vowel phonation also frequently develops into tone, as can be seen in the case of Burmese.

Tone arose in the Athabascan languages at least twice, in a patchwork of two systems. In some languages, such as Navajo, syllables with glottalized consonants (including glottal stops) in the syllable coda developed low tones, whereas in others, such as Slavey, they developed high tones, so that the two tonal systems are almost mirror images of each other. Syllables without glottalized codas developed the opposite tone—for example, high tone in Navajo and low tone in Slavey, due to contrast with the tone triggered by the glottalization. Other Athabascan languages, namely those in western Alaska (such as Koyukon) and the Pacific coast (such as Hupa), did not develop tone. Thus, the Proto-Athabascan word for "water"  is toneless  in Hupa, high-tone  in Navajo, and low-tone tù in Slavey; while Proto-Athabascan  "knee" is toneless  in Hupa, low-tone  in Navajo, and high-tone  in Slavey. Kingston (2005) provides a phonetic explanation for the opposite development of tone based on the two different ways of producing glottalized consonants with either (a) tense voice on the preceding vowel, which tends to produce a high F0, or (b) creaky voice, which tends to produce a low F0. Languages with "stiff" glottalized consonants and tense voice developed high tone on the preceding vowel and those with "slack" glottalized consonants with creaky voice developed low tone.

The Bantu languages also have "mirror" tone systems, where the languages in the northwest corner of the Bantu area have the opposite tones of other Bantu languages.

Three Algonquian languages developed tone independently of each other and of neighboring languages: Cheyenne, Arapaho, and Kickapoo. In Cheyenne, tone arose via vowel contraction; the long vowels of Proto-Algonquian contracted into high-pitched vowels in Cheyenne, while the short vowels became low-pitched. In Kickapoo, a vowel with a following [h] acquired a low tone, and this tone later extended to all vowels followed by a fricative.

In Mohawk, a glottal stop can disappear in a combination of morphemes, leaving behind a long falling tone. Note that this has the reverse effect of the postulated rising tone in Mandarin derived from a lost final glottal stop.

See also
 Meeussen's rule
 Tone name
 Tone number
 Tone pattern
 Musical language
 Lion-Eating Poet in the Stone Den

References

Bibliography
 Bao, Zhiming. (1999). The structure of tone. New York: Oxford University Press. ISBN 0-19-511880-4.
Chen, Matthew Y. 2000. Tone Sandhi: patterns across Chinese dialects. Cambridge, England: CUP ISBN 0-521-65272-3
Clements, George N.; Goldsmith, John (eds.) (1984) Autosegmental Studies in Bantu Tone. Berlin: Mouton de Gruyer.
 Fromkin, Victoria A. (ed.). (1978). Tone: A linguistic survey. New York: Academic Press.
 Halle, Morris; & Stevens, Kenneth. (1971). A note on laryngeal features. Quarterly progress report 101. MIT.
 Haudricourt, André-Georges. (1954). "De l'origine des tons en vietnamien". Journal Asiatique, 242: 69–82.
 Haudricourt, André-Georges. (1961). "Bipartition et tripartition des systèmes de tons dans quelques langues d'Extrême-Orient". Bulletin de la Société de Linguistique de Paris, 56: 163–180.
 
 Hyman, Larry. 2007. There is no pitch-accent prototype. Paper presented at the 2007 LSA Meeting. Anaheim, CA.
 Hyman, Larry. 2007. How (not) to do phonological typology: the case of pitch-accent. Berkeley, UC Berkeley. UC Berkeley Phonology Lab Annual Report: 654–685. Available online.
 Kingston, John. (2005). The phonetics of Athabaskan tonogenesis. In S. Hargus & K. Rice (Eds.), Athabaskan prosody (pp. 137–184). Amsterdam: John Benjamins Publishing.
 Maddieson, Ian. (1978). Universals of tone. In J. H. Greenberg (Ed.), Universals of human language: Phonology (Vol. 2). Stanford: Stanford University Press.
 Michaud, Alexis. (2008). Tones and intonation: some current challenges. Proc. of 8th Int. Seminar on Speech Production (ISSP'08), Strasbourg, pp. 13–18. (Keynote lecture.) Available online.
 Odden, David. (1995). Tone: African languages. In J. Goldsmith (Ed.), Handbook of phonological theory. Oxford: Basil Blackwell.
 Pike, Kenneth L. (1948). Tone languages: A technique for determining the number and type of pitch contrasts in a language, with studies in tonemic substitution and fusion. Ann Arbor: The University of Michigan Press. (Reprinted 1972, ISBN 0-472-08734-7).
 
 Yip, Moira. (2002). Tone. Cambridge textbooks in linguistics. Cambridge: Cambridge University Press. ISBN 0-521-77314-8 (hbk), ISBN 0-521-77445-4 (pbk).

External links

 World map of tone languages The World Atlas of Language Structures Online