Front vowel

Front vowels are a class of vowel sounds used in spoken languages that are produced when the tongue is positioned toward the front of the mouth. Front vowels appear in most of the world's languages, with [i] and [e] being present in 92% and 61% of languages according to PHOIBLE.

Front vowels can be rounded, but are typically unrounded, meaning that the lips are relaxed while speakers are producing them. This is because languages want to maximize the degree of contrast between vowels. Rounding has the effect of bringing a vowel further back in the mouth, so across the world's languages, it's more common for front vowels to be unrounded than rounded, and for back vowels to be rounded rather than unrounded. This is reflected in the position of rounded front vowels on the IPA vowel chart. They are written to the right of the unrounded front vowels to note that they are typically centralized.