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In phonetics, a vowel is a sound in spoken language, such as an English "ah!" or "oh!" . There are two competing definitions of a vowel. In the more common phonetic definition, a vowel is a sound pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis. This contrasts with consonants, such as English "sh!" , which have a constriction or closure at some point along the vocal tract. In the other, phonological definition, a vowel is defined as syllabic, the sound that forms the peak of a syllable. A phonetically equivalent but non-syllabic sound is a semivowel. In oral languages, phonetic vowels normally form the peak (nucleus) of many to all syllables, whereas consonants form the onset and (in languages that have them) coda. Some languages allow other sounds to form the nucleus of a syllable, such as the syllabic ''l'' in the English word ''table'' (when not considered to have a weak vowel sound: ) or the syllabic ''r'' in Serbo-Croatian word ''vrt'' "garden". The word ''vowel'' comes from the Latin word ''vocalis'', meaning "vocal" ("relating to voice").〔(【引用サイトリンク】url=http://www.etymonline.com/index.php?term=vowel )〕 In English, the word ''vowel'' is commonly used to mean both vowel sounds and the written symbols that represent them. ==Definition of "vowel"== The phonetic definition of "vowel" (a sound produced with no constriction in the vocal tract) does not always match the phonological definition (a sound that forms the peak of a syllable).〔Laver, John (1994) ''Principles of Phonetics'', Cambridge: Cambridge University Press, p. 269.〕 The approximants and illustrate this: both are produced without much of a constriction in the vocal tract (so phonetically they seem to be vowel-like), but they occur on the edge of syllables (e.g. in "yet" and "wet") (which suggests that phonologically they are consonants). A similar debate arises over whether a word like ''bird'' in a rhotic dialect has an r-colored vowel or a syllabic consonant . The American linguist Kenneth Pike (1943) suggested the terms "vocoid" for a phonetic vowel and "vowel" for a phonological vowel,〔Crystal, David (2005) ''A Dictionary of Linguistics & Phonetics (Fifth Edition)'', Maldern, MA/Oxford: Blackwell, p. 494.〕 so using this terminology, and are classified as vocoids but not vowels. However, Maddieson and Emmory (1985) demonstrated from a range of languages that semivowels are produced with a narrower constriction of the vocal tract than vowels, and so may be considered consonants on that basis. Nonetheless, the phonetic and phonemic definitions would still conflict for the syllabic el in ''table'', or the syllabic nasals in ''button'' and ''rhythm''. ==Articulation== The traditional view of vowel production, reflected for example in the terminology and presentation of the International Phonetic Alphabet, is one of articulatory features that determine a vowel's ''quality'' as distinguishing it from other vowels. Daniel Jones developed the cardinal vowel system to describe vowels in terms of the features of tongue ''height'' (vertical dimension), tongue ''backness'' (horizontal dimension) and ''roundedness'' (lip articulation). These three parameters are indicated in the schematic quadrilateral IPA vowel diagram on the right. There are additional features of vowel quality, such as the velum position (nasality), type of vocal fold vibration (phonation), and tongue root position. This conception of vowel articulation has been known to be inaccurate since 1928. Peter Ladefoged has said ''early phoneticians ... thought they were describing the highest point of the tongue, but they were not. They were actually describing formant frequencies.''〔Ladefoged & Disner (2012) ''Vowels and Consonants'', 3rd ed., p. 132.〕 (See below.) The IPA ''Handbook'' concedes that ''the vowel quadrilateral must be regarded as an abstraction and not a direct mapping of tongue position.''〔IPA (1999) ''Handbook of the IPA'', p. 12.〕 Nonetheless, the concept that vowel qualities are determined primarily by tongue position and lip rounding continues to be used in pedagogy, as it provides an intuitive explanation of how vowels are distinguished. ===Height=== (詳細はjaw. However, it actually refers to the first formant (lowest resonance of the voice), abbreviated F1, which is associated with the height of the tongue. In close vowels, also known as high vowels, such as and , the first formant is consistent with the tongue being positioned close to the palate, high in the mouth, whereas in open vowels, also known as low vowels, such as , F1 is consistent with the jaw being open and the tongue being positioned low in the mouth. Height is defined by the inverse of the F1 value: The higher the frequency of the first formant, the lower (more open) the vowel.〔According to Peter Ladefoged, traditional articulatory descriptions such as height and backness "are not entirely satisfactory", and when phoneticians describe a vowel as high or low, they are in fact describing an acoustic quality rather than the actual position of the tongue. Ladefoged, Peter (2006) ''A Course in Phonetics (Fifth Edition)'', Boston, MA: Thomson Wadsworth, p. 189.〕 The International Phonetic Alphabet defines seven degrees of vowel height: * close (high) * near-close (near-high) * close-mid (high-mid) * mid (true-mid) * open-mid (low-mid) * near-open (near-low) * open (low) The letters are typically used for either close-mid or true-mid vowels. However, if more precision is required, true-mid vowels may be written with a lowering diacritic . The Kensiu language spoken in Malaysia and Thailand is highly unusual in that it contrasts true-mid with close-mid and open-mid vowels without differences in other parameters such as backness or roundness. Although English contrasts six heights in its vowels, these are interdependent with differences in backness, and many are parts of diphthongs. It appears that some varieties of German have five contrasting vowel heights independently of length or other parameters. The Bavarian dialect of Amstetten has thirteen long vowels, reported to distinguish five heights (close, close-mid, mid, open-mid and open) each among the front unrounded, front rounded, and back rounded vowels, plus an open central vowel, thus five vowel heights on the whole: . Otherwise, languages are not known to contrast more than four degrees of vowel height. The parameter of vowel height appears to be the primary cross-linguistic feature of vowels in that all languages use height as a contrastive feature. No other parameter, not even backness or rounding (see below), is used in all languages. Some languages have vertical vowel systems in which, at least at a phonemic level, only height is used to distinguish vowels. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「vowel」の詳細全文を読む スポンサード リンク
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