Tone (linguistics)

Tone, in a language, is the use of pitch contour, pitch register, or both to distinguish lexical or grammatical meaning—that is, to distinguish or to inflect words. All oral languages use pitch to express emotional and other para-linguistic information and to convey emphasis, contrast and other such features in what is called intonation, but not all languages use tones to distinguish words or their inflections, analogously to consonants and vowels. Languages that have this feature are called tonal languages; the distinctive tone patterns of such a language are sometimes called tonemes, by analogy with phoneme. Tonal languages are common in East and Southeast Asia, Africa, the Americas, and the Pacific.
Tonal languages are different from pitch-accent languages in that tonal languages can have each syllable with an independent tone whilst pitch-accent languages may have one syllable in a word or morpheme that is more prominent than the others.

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 exist between syllables with the same segmental features but different tones. Vietnamese and Chinese have heavily studied tone systems, as well as amongst their various dialects.
Below is a table of the six Vietnamese tones and their corresponding tone accent or diacritics:
Mandarin Chinese, which has five tones, transcribed by letters with diacritics over vowels:

A high level tone: /á/
A tone starting with mid pitch and rising to a high pitch: /ǎ/
A low tone with a slight fall : /à/
A short, sharply falling tone, starting high and falling to the bottom of the speaker's vocal range: /â/
A neutral tone, with no specific contour, used on weak syllables; its pitch depends chiefly on the tone of the preceding syllable.

These tones combine with a syllable such as ma to produce different words. A minimal set based on ma are, in pinyin transcription:

mā 'mother'
má 'hemp'
mǎ 'horse'
mà 'scold'
ma

These may be combined into a tongue-twister:
See also one-syllable article.
A well-known tongue-twister in Standard Thai is:
A Vietnamese tongue twister:
A Cantonese tongue twister:
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. It is also possible for lexically contrastive pitch to span entire words or morphemes instead of manifesting on the syllable nucleus, which is the case in Punjabi.
Tones can interact in complex ways through a process known as tone sandhi.

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 glottalization 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. The distinctions of such systems are termed registers. The tone register here should not be confused with register tone described in the next section.

Phonation type

Gordon and Ladefoged established a continuum of phonation, where several types can be identified.

Relationship with tone

Kuang identified two types of phonation: pitch-dependent and pitch-independent. Contrast of tones has long been thought of as differences in pitch height. However, several studies pointed out that tone is actually multidimensional. Contour, duration, and phonation may all contribute to the differentiation of tones. Investigations from the 2010s using perceptual experiments seem to suggest phonation counts as a perceptual cue.

Tone and pitch accent

Many languages use tone in a more limited way. In Japanese, fewer than half of the words have a 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.

Tone and intonation

Both lexical or grammatical tone and prosodic intonation are cued by changes in pitch, as well as sometimes by changes in phonation. Lexical tone coexists with intonation, with the lexical changes of pitch like waves superimposed on larger swells. For example, Luksaneeyanawin describes three intonational patterns in Thai: falling, rising and "convoluted". The phonetic realization of these intonational patterns superimposed on the five lexical tones of Thai are as follows:

	Falling intonation	Rising intonation	Convoluted intonation
High level tone
Mid level tone
Low level tone
Falling tone
Rising tone

With convoluted intonation, it appears that high and falling tone conflate, while the low tone with convoluted intonation has the same contour as rising tone with rising intonation.

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, whereas 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.

Types

Register tones and contour tones

In many Bantu languages, tones are distinguished by their pitch level relative to each other. 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. Many words, especially monosyllabic ones, 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 the grammar of modern standard Chinese, though the tones descend from features in Old Chinese that had morphological significance.
Most tonal languages have a combination of register and contour tones. Tone is typical of languages including Kra–Dai, Vietic, Sino-Tibetan, Afroasiatic, Khoisan, Niger-Congo and Nilo-Saharan languages. Most tonal languages combine both register and contour tones, such as Cantonese, which produces three varieties of contour tone at three different pitch levels, and the Omotic language Bench, which employs five level tones and one or two rising tones across levels.
Most varieties of Chinese use contour tones, where the distinguishing feature of the tones are their shifts in pitch, such as rising, falling, dipping, or level. Most Bantu languages on the other hand, have simpler tone systems usually with high, low and one or two contour tone. 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 and other Niger-Congo languages of West Africa.
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.

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 Kru languages, each syllable may have a tone, whereas in Shanghainese, Swedish, Norwegian 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 than a monosyllabic word, 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 Chinese suffixes and grammatical particles have what is called 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	Example	Pinyin	English meaning
high		玻璃	bōli	glass
rising		伯伯	bóbo	elder uncle
dipping		喇叭	lǎba	horn
falling		兔子	tùzi	rabbit

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.