High Quality Content by WIKIPEDIA articles! The voiceless glottal transition, commonly called a "fricative", is a type of sound used in some spoken languages which often behaves like a fricative, but sometimes behaves more like an approximant or is indeterminate in its behavior. The symbol in the International Phonetic Alphabet that represents this sound is h, and the equivalent X-SAMPA symbol is h. Although [h] has been described as a voiceless vowel, because in many languages it lacks the place and manner of articulation of a prototypical consonant, it also lacks the height and backness of a prototypical vowel.