In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are [p] and [b], pronounced with the lips; [t] and [d], pronounced with the front of the tongue; [k] and [g], pronounced with the back of the tongue; [h], pronounced in the throat; [f], [v], and [s], pronounced by forcing air through a narrow channel (fricatives); and [m] and [n], which have air flowing through the nose (nasals). Contrasting with consonants are vowels.
Since the number of speech sounds in the world's languages is much greater than the number of letters in any one alphabet, linguists have devised systems such as the International Phonetic Alphabet (IPA) to assign a unique and unambiguous symbol to each attested consonant. The English alphabet has fewer consonant letters than the English language has consonant sounds, so digraphs like ⟨ch⟩, ⟨sh⟩, ⟨th⟩, and ⟨ng⟩ are used to extend the alphabet, though some letters and digraphs represent more than one consonant. For example, the sound spelled ⟨th⟩ in "this" is a different consonant from the ⟨th⟩ sound in "thin". (In the IPA, these are [ð] and [θ], respectively.)
Dionysius Thrax calls consonants sýmphōna (σύμφωνα 'sounded with') because in Greek they can only be pronounced with a vowel.[a] He divides them into two subcategories: hēmíphōna (ἡμίφωνα 'half-sounded'), which are the continuants,[b] and áphōna (ἄφωνος 'unsounded'), which correspond to plosives.[c]
This description does not apply to some languages, such as the Salishan languages, in which plosives may occur without vowels (see Nuxalk), and the modern concept of 'consonant' does not require co-occurrence with a vowel.
The word consonant may be used ambiguously for both speech sounds and the letters of the alphabet used to write them. In English, these letters are B, C, D, F, G, J, K, L, M, N, P, Q, S, T, V, X, Z and often H, R, W, Y.
In English orthography, the letters H, R, W, Y and the digraph GH are used for both consonants and vowels. For instance, the letter Y stands for the consonant /j/ in yoke, the vowel /ɪ/ in myth, the vowel /i/ in funny, the diphthong /aɪ/ in sky, and forms several digraphs for other diphthongs, such as say, boy, key. Similarly, R commonly indicates or modifies a vowel in non-rhotic accents.
This article is concerned with consonant sounds, however they are written.
Consonants and vowels correspond to distinct parts of a syllable: The most sonorous part of the syllable (that is, the part that's easiest to sing), called the syllabic peak or nucleus, is typically a vowel, while the less sonorous margins (called the onset and coda) are typically consonants. Such syllables may be abbreviated CV, V, and CVC, where C stands for consonant and V stands for vowel. This can be argued to be the only pattern found in most of the world's languages, and perhaps the primary pattern in all of them. However, the distinction between consonant and vowel is not always clear cut: there are syllabic consonants and non-syllabic vowels in many of the world's languages.
One blurry area is in segments variously called semivowels, semiconsonants, or glides. On one side, there are vowel-like segments that are not in themselves syllabic, but form diphthongs as part of the syllable nucleus, as the i in English boil [ˈbɔɪ̯l]. On the other, there are approximants that behave like consonants in forming onsets, but are articulated very much like vowels, as the y in English yes [ˈjɛs]. Some phonologists model these as both being the underlying vowel /i/, so that the English word bit would phonemically be /bit/, beet would be /bii̯t/, and yield would be phonemically /i̯ii̯ld/. Likewise, foot would be /fut/, food would be /fuu̯d/, wood would be /u̯ud/, and wooed would be /u̯uu̯d/. However, there is a (perhaps allophonic) difference in articulation between these segments, with the [j] in [ˈjɛs] yes and [ˈjiʲld] yield and the [w] of [ˈwuʷd] wooed having more constriction and a more definite place of articulation than the [ɪ] in [ˈbɔɪ̯l] boil or [ˈbɪt] bit or the [ʊ] of [ˈfʊt] foot.
The other problematic area is that of syllabic consonants, segments articulated as consonants but occupying the nucleus of a syllable. This may be the case for words such as church in rhotic dialects of English, although phoneticians differ in whether they consider this to be a syllabic consonant, /ˈtʃɹ̩tʃ/, or a rhotic vowel, /ˈtʃɝtʃ/: Some distinguish an approximant /ɹ/ that corresponds to a vowel /ɝ/, for rural as /ˈɹɝl/ or [ˈɹʷɝːl̩]; others see these as a single phoneme, /ˈɹɹ̩l/.
Other languages use fricative and often trilled segments as syllabic nuclei, as in Czech and several languages in Democratic Republic of the Congo, and China, including Mandarin Chinese. In Mandarin, they are historically allophones of /i/, and spelled that way in Pinyin. Ladefoged and Maddieson[page needed] call these "fricative vowels" and say that "they can usually be thought of as syllabic fricatives that are allophones of vowels". That is, phonetically they are consonants, but phonemically they behave as vowels.
Many Slavic languages allow the trill [r̩] and the lateral [l̩] as syllabic nuclei (see Words without vowels). In languages like Nuxalk, it is difficult to know what the nucleus of a syllable is, or if all syllables even have nuclei. If the concept of 'syllable' applies in Nuxalk, there are syllabic consonants in words like /sx̩s/ (/s̩xs̩/?) 'seal fat'. Miyako in Japan is similar, with /f̩ks̩/ 'to build' and /ps̩ks̩/ 'to pull'.
Each spoken consonant can be distinguished by several phonetic features:
All English consonants can be classified by a combination of these features, such as "voiceless alveolar stop" [t]. In this case, the airstream mechanism is omitted.
The recently extinct Ubykh language had only 2 or 3 vowels but 84 consonants; the Taa language has 87 consonants under one analysis, 164 under another, plus some 30 vowels and tone. The types of consonants used in various languages are by no means universal. For instance, nearly all Australian languages lack fricatives; a large percentage of the world's languages lack voiced stops such as /b/, /d/, /ɡ/ as phonemes, though they may appear phonetically. Most languages, however, do include one or more fricatives, with /s/ being the most common, and a liquid consonant or two, with /l/ the most common. The approximant /w/ is also widespread, and virtually all languages have one or more nasals, though a very few, such as the Central dialect of Rotokas, lack even these. This last language has the smallest number of consonants in the world, with just six.
The most frequent consonants in rhotic American English (that is, the ones appearing most frequently during speech) are /n, ɹ, t/. (/ɹ/ is less common in non-rhotic accents.) The most frequent consonant in many other languages is /p/.
The most universal consonants around the world (that is, the ones appearing in nearly all languages) are the three voiceless stops /p/, /t/, /k/, and the two nasals /m/, /n/. However, even these common five are not completely universal. Several languages in the vicinity of the Sahara Desert, including Arabic, lack /p/. Several languages of North America, such as Mohawk, lack both of the labials /p/ and /m/. The Wichita language of Oklahoma and some West African languages, such as Ijo, lack the consonant /n/ on a phonemic level, but do use it phonetically, as an allophone of another consonant (of /l/ in the case of Ijo, and of /ɾ/ in Wichita). A few languages on Bougainville Island and around Puget Sound, such as Makah, lack both of the nasals [m] and [n] altogether, except in special speech registers such as baby-talk. The 'click language' Nǁng lacks /t/,[d] and colloquial Samoan lacks both alveolars, /t/ and /n/.[e] Despite the 80-odd consonants of Ubykh, it lacks the plain velar /k/ in native words, as do the related Adyghe and Kabardian languages. But with a few striking exceptions, such as Xavante and Tahitian—which have no dorsal consonants whatsoever—nearly all other languages have at least one velar consonant: most of the few languages that do not have a simple /k/ (that is, a sound that is generally pronounced [k]) have a consonant that is very similar.[f] For instance, an areal feature of the Pacific Northwest coast is that historical *k has become palatalized in many languages, so that Saanich for example has /tʃ/ and /kʷ/ but no plain /k/; similarly, historical *k in the Northwest Caucasian languages became palatalized to /kʲ/ in extinct Ubykh and to /tʃ/ in most Circassian dialects.
The following pages include consonant charts with links to audio samples.