The open central unrounded vowel, or low central unrounded vowel, is a type of vowel sound, used in many spoken languages. While the International Phonetic Alphabet officially has no dedicated letter for this sound between front and back , it is normally written . If precision is required, it can be specified by using diacritics, such as centralized or retracted , but this is not common.

The open front unrounded vowel, or low front unrounded vowel, is a type of vowel sound, used in some spoken languages. 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.