The open front unrounded vowel, or low front unrounded vowel, is a type of vowel sound, used in some spokenlanguages. It is one of the eight primary cardinal vowels, not directly intended to correspond to a vowel sound of a specific language but rather to serve as a fundamental reference point in a phonetic measuring system.
The symbol in the International Phonetic Alphabet (IPA) that represents this sound is ⟨a⟩, and in the IPA vowel chart it is positioned at the lower-left corner. However, the accuracy of the quadrilateral vowel chart is disputed, and the sound has been analyzed acoustically as an extra-open/low unrounded vowel at a position where the front/back distinction has lost its significance. There are also differing interpretations of the exact quality of the vowel: the classic sound recording of [a] by Daniel Jones is slightly more front but not quite as open as that by John Wells.
In practice, it is considered normal by many phoneticians to use the symbol ⟨a⟩ for an open central unrounded vowel and instead approximate the open front unrounded vowel with ⟨æ⟩ (which officially signifies a near-open front unrounded vowel). This is the usual practice, for example, in the historical study of the English language. The loss of separate symbols for open and near-open front vowels is usually considered unproblematic, because the perceptual difference between the two is quite small, and very few languages contrast the two. If there is a need to specify the backness of the vowel as fully front one can use the symbol ⟨æ̞⟩, which denotes a lowered near-open front unrounded vowel.
Its vowel height is open, also known as low, which means the tongue is positioned as far as possible from the roof of the mouth – that is, as low as possible in the mouth.
Its vowel backness is front, which means the tongue is positioned as far forward as possible in the mouth without creating a constriction that would be classified as a consonant. Note that rounded front vowels are often centralized, which means that often they are in fact near-front. This subsumes central open (central low) vowels because the tongue does not have as much flexibility in positioning as it does in the mid and close (high) vowels; the difference between an open front vowel and an open back vowel is similar to the difference between a close front and a close central vowel, or a close central and a close back vowel.
It is unrounded, which means that the lips are not rounded.
Many languages have some form of an unrounded open vowel. For languages that have only a single open vowel, the symbol for this vowel ⟨a⟩ may be used because it is the only open vowel whose symbol is part of the basic Latin alphabet. Whenever marked as such, the vowel is closer to a central [ä] than to a front [a].
^ abcdThomas (2004:308): A few younger speakers from, e.g., Texas, who show the LOT/THOUGHT merger have TRAP shifted toward [a], but this retraction is not yet as common as in some non-Southern regions (e.g., California and Canada), though it is increasing in parts of the Midwest on the margins of the South (e.g., central Ohio).
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