Voiceless glottal fricative

A voiceless glottal fricative, sometimes called a voiceless glottal transition or an aspirate, is a type of sound used in some spoken languages. It is familiar to English-speakers as the "h" sound in "hut". The symbol in the International Phonetic Alphabet that represents this sound is ⟨h⟩.

A [h] sound may have real glottal constriction in a number of languages (such as Arabic), making it a true fricative. However, in many languages that have it, it only patterns like a fricative or approximant phonologically, and lacks the usual phonetic characteristics of a consonant. In such languages, [h] has no inherent place or manner of articulation, as well as lacking the height and backness of a vowel. Thus it has been described as neither consonant nor vowel but simply voiceless phonation:

[h and ɦ] have been described as voiceless or breathy voiced counterparts of the vowels that follow them [but] the shape of the vocal tract [...] is often simply that of the surrounding sounds. [...] Accordingly, in such cases it is more appropriate to regard h and ɦ as segments that have only a laryngeal specification, and are unmarked for all other features. There are other languages [such as Hebrew and Arabic] which show a more definite displacement of the formant frequencies for h, suggesting it has a [glottal] constriction associated with its production.

An effort was undertaken at the Kiel Convention in 1989 to move glottal fricatives, both voiceless and voiced, to the approximant cells of the IPA chart. A specifically fricative sound may be indicated with a raising diacritic ⟨h̝⟩, and a specifically approximant with a lowering diacritic ⟨h̞⟩.

The Shanghainese language, among others, contrasts voiced and voiceless glottal fricatives.