What is a closed vowel?

A closed vowel is a type of vowel sound in which the tongue is positioned high in the mouth, close to the roof, during articulation. This positioning results in a relatively small space between the tongue and the roof of the mouth. Examples of closed vowels in English include the sounds in Words like "beat" (i) and "boot" (u). These vowels contrast with open vowels, where the tongue is positioned lower, creating a larger space.