Glottal consonant

Glottal consonants, also called laryngeal consonants, are consonants articulated with the glottis. Many phoneticians consider them, or at least the so-called fricative, to be transitional states of the glottis without a point of articulation as other consonants have; some do not at all consider them to be consonants. However, glottal consonants behave as typical consonants in many languages. For example, in Literary Arabic, most words are formed from a root C-C-C consisting of three consonants, which are inserted into templates such as or. The glottal consonants and  can occupy any of the three root consonant slots, just like "normal" consonants such as  or.

Glottal consonant in IPA
Glottal consonants in the International Phonetic Alphabet:

Characteristics
The "fricatives" are not true fricatives. This is a historical usage of the word. They instead represent transitional states of the glottis (phonation) without a specific place of articulation. is a voiceless transition. is a breathy-voiced transition, and could be transcribed as.

The glottal stop occurs in many languages. Often all vocalic onsets are preceded by a glottal stop, for example in German. The Hawaiian language writes the glottal stop as an opening single quote ‘. Some alphabets use diacritics for the glottal stop, such as hamza $\langleء\rangle$ in the Arabic alphabet; in many languages of Mesoamerica, the Latin letter $\langleh\rangle$ is used for glottal stop, while in Maltese, the letter $\langleq\rangle$ is used instead.

Because the glottis is necessarily closed for the glottal stop, it cannot be voiced.

Laryngeal consonants
The term "laryngeal consonant" is generally synonymous with "glottal consonant"; that is, it refers to, , and.

Besides the glottis (vocal folds), the larynx includes the epiglottis and aryepiglottic folds, though epiglottal and aryepiglottal consonants are usually counted as radical rather than as laryngeal. However, the diversity of sounds produced in the larynx is the subject of ongoing research, and the terminology is evolving.

The term laryngeal consonant is also used for laryngealized consonants articulated in the upper vocal tract, such as Arabic 'emphatics' and Korean 'tense' consonants.