A slight majority of the languages in the world are tonal. However, most Indo-European languages, which include the most widely spoken languages in the world today, are not tonal.
In the most familiar tonal language, Chinese, tones are distinguished by their shape (contour), most syllables carry their own tone, words tend to be short, and many words are differentiated solely by tone. (This is more true in Cantonese than Mandarin.) Tone also plays almost no grammatical role. In many African tone languages, such as most Bantu languages, however, tones are distinguished by their relative level, words are longer, there are fewer minimal tone pairs, and 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.
Many languages use tone in a more limited way. Somali, for example, may only have one high tone per word. In Japanese, less 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, the term "pitch accent" does not have a coherent definition.
The vast majority of Austronesian languages are non-tonal, but a small number have developed tone. No tonal language has been reported from Australia. With other languages we simply don't know. 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.
A famous example of tone in Ancient Greek comes from Aristophanes' Frogs, where (l. 304) Aristophanes mentions an instance at a performance of Euripides' play Orestes, where an actor pronounced galḗn' horō "I see calm waters" with so much empathy that it came out galên horō "I see a weasel".
Here is a minimal tone set from Mandarin Chinese, which has five tones, here transcribed by diacritics over the vowels:
These tones combine with a syllable such as "ma" to produce different words. A minimal set based on "ma" are, in pinyin transcription,
These may be combined into the rather contrived sentence,
A well-known tongue-twister in the Thai language is:
Tones can interact in complex ways through a process known as tone sandhi.
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 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 many register tone 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 register and contour tones, such as many Kru languages, where nouns are distinguished by contour tones and verbs by register. Others, such as Yoruba, have phonetic contours, but these can easily be analysed as sequences of register tones, with for example sequences of high–low /áà/ becoming falling [âː], and sequences of low–high /àá/ becoming rising [ǎː].
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 two 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.
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.
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:
|Tone in isolation|| Tone pattern with|
added 'neutral tone'
After high level and high rising tones, the neutral syllable has an independent pitch that looks like a mid register tone the 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.
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.
More iconic systems are to 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):
|High tone||55||˥˥||(Tone 1)|
|Mid rising tone||35||˧˥||(Tone 2)|
|Low dipping tone||214||˨˩˦||(Tone 3)|
|High falling tone||51||˥˩||(Tone 4)|
Standard IPA notation is also sometimes seen for Chinese. One reason it is not more widespread is that only two contour tones, rising /ɔ̌/ and falling /ɔ̂/, 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 /ɔ̌/ and /ɔ̂/ for high-rising (/35/) and high-falling (/53/) tones, and to use the subscript diacritics /ɔ̗/ and /ɔ̖/ for low-rising (/13/) and low-falling (/31/) tones.
The Thai language has five tones: high, mid, low, rising and falling. It uses an alphabetic writing system 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 is still debatable. Notation for Vietnamese tones are as follows:
|ngang||mid level, ˧||not marked||a|
|huyền||low falling, ˨˩||grave accent||à|
|sắc||high rising, ˧˥||acute accent||á|
|ngã||creaky rising, ˧ˀ˥||tilde||ã|
|nặng||creaky falling, ˧ˀ˨||dot below||ạ|
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 typewriter 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.
In Mesoamericanist linguistics, /1/ stands for High tone and /5/ stands for Low 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 notoriously tonal and is the largest language family in Mesoamerica, containing languages including Zapotec, Mixtec, Chinantec, and Otomí, some of which have as many as 12 different tones (Zoogocho Zapotec) and others only two (Matlatzinca and Chichimeca Jonaz). Other languages in Mesoamerica that have tones are Huichol, Yukatek Maya, Tzotzil Maya of San Bartolo and Uspantec Maya (Quiché of Uspantán), and one variety of Huave.
A number of languages of South America are tonal. For example, the Pirahã language has three tones. The Ticuna language isolate is exceptional for having five level tones (the only other languages to have such a system are the Trique language and the Usila dialect of Chinantec (both Oto-Manguean languages of Mexico).
If we include contour tones as separate tones, several Kam-Sui languages of southern China have nine tones, assuming that final consonants are not counted as additional tones, as they traditionally are in China. One of them, Ai-Cham (錦話), is said to have eleven tones.
Preliminary work on the Wobe language of Liberia and Ivory Coast 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 two tones.
Very often, tone arises as an effect of the loss or merger of consonants. (Such trace effects of disappeared sounds, which is not restricted to tone, 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). We can see this 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 high 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 "leaving" tones, arose as the Old Chinese final consonants /ʔ/ 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 split in two depending on whether the initial consonant was voiced: Vowels following an unvoiced consonant acquired a higher tone while those following a voiced consonant acquired a lower tone as the voiced consonants lost their 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" *tuː is toneless toː in Hupa, high-tone tó in Navajo, and low-tone tù in Slavey; while Proto-Athabascan *-ɢʊtʼ "knee" is toneless -ɢotʼ in Hupa, low-tone -ɡòd in Navajo, and high-tone -góʼ 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.