Vowel
![X-rays of Daniel Jones' [i, u, a, ɑ].](/uploads/202502/20/Cardinal_vowels-Jones_x-ray5441.jpg)
![The original vowel quadrilateral, from Jones' articulation. The vowel trapezoid of the modern IPA, and at the top of this article, is a simplified rendition of this diagram. The bullets are the cardinal vowel points. (A parallel diagram covers the front and central rounded and back unrounded vowels.) The cells indicate the ranges of articulation that could reasonably be transcribed with those cardinal vowel letters, [i, e, ɛ, a, ɑ, ɔ, o, u, ɨ], and non-cardinal [ə]. If a language distinguishes fewer than these vowel qualities, [e, ɛ] could be merged to [e], [o, ɔ] to [o], [a, ɑ] to [a], etc. If a language distinguishes more, [j] could be added where the ranges of [i, e, ɨ, ə] intersect, [ʊ] where [u, o, ɨ, ə] intersect, and [ɐ] where [ɛ, ɔ, a, ɑ, ə] intersect.](/uploads/202502/20/Vowel_quadrilateral_(IPA_1949)5441.png)
In phonetics, a vowel is a sound in spoken language, with two competing definitions. In the more common phonetic definition, a vowel is a sound pronounced with an open vocal tract, so that the tongue does not touch the lips, teeth, or roof of the mouth, such as the English "ah" /ɑː/ or "oh" /oʊ/. There is no build-up of air pressure at any point above the glottis. This contrasts with consonants, such as the English "sh" [ʃː], 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.