The glottis is defined as the combination of the vocal folds

Vocal folds

The vocal folds, also known commonly as vocal cords, are composed of twin infoldings of mucous membrane stretched horizontally across the larynx...

 (vocal cords) and the space in between the folds (the rima glottidis

Rima glottidis

The rima glottidis is the opening between the true vocal cords and the arytenoid cartilages.It is normally subdivided into two parts, that between the arytenoid cartilages is called the intercartilaginous part , and that between the vocal folds the intermembranous part or glottis vocalis.It is...

).

Function

As the vocal folds vibrate, the resulting vibration produces a "buzzing" quality to the speech, called voice

Voice (phonetics)

Voice or voicing is a term used in phonetics and phonology to characterize speech sounds, with sounds described as either voiceless or voiced. The term, however, is used to refer to two separate concepts. Voicing can refer to the articulatory process in which the vocal cords vibrate...

or voicing or pronunciation.

Sound production involving only the glottis is called glottal. English has a voiceless glottal fricative

Voiceless glottal fricative

The voiceless glottal transition, commonly called a "fricative", is a type of sound used in some spoken languages which patterns like a fricative or approximant consonant phonologically, but often lacks the usual phonetic characteristics of a consonant...

 spelled "h". In many accents of English the glottal stop

Glottal stop

The glottal stop, or more fully, the voiceless glottal plosive, is a type of consonantal sound used in many spoken languages. In English, the feature is represented, for example, by the hyphen in uh-oh! and by the apostrophe or [[ʻokina]] in Hawaii among those using a preservative pronunciation of...

 (made by pressing the folds together) is used as a variant allophone

Allophone

In phonology, an allophone is one of a set of multiple possible spoken sounds used to pronounce a single phoneme. For example, and are allophones for the phoneme in the English language...

 of the phoneme /t/ (and in some dialects, occasionally of /k/ and /p/); in some languages, this sound is a phoneme

Phoneme

In a language or dialect, a phoneme is the smallest segmental unit of sound employed to form meaningful contrasts between utterances....

 of its own.

Skilled players of the Australian didgeridoo

Didgeridoo

The didgeridoo is a wind instrument developed by Indigenous Australians of northern Australia around 1,500 years ago and still in widespread usage today both in Australia and around the world. It is sometimes described as a natural wooden trumpet or "drone pipe"...

 restrict their glottal opening in order to produce the full range of timbres available on the instrument.

The vibration produced is an essential component of voiced consonant

Consonant

In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are , pronounced with the lips; , pronounced with the front of the tongue; , pronounced with the back of the tongue; , pronounced in the throat; and ,...

s as well as vowel

Vowel

In phonetics, a vowel is a sound in spoken language, such as English ah! or oh! , pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis. This contrasts with consonants, such as English sh! , where there is a constriction or closure at some...

s. If the vocal folds are drawn apart, air flows between them causing no vibration, as in the production of voiceless consonants.

The glottis is also important in the valsalva maneuver

Valsalva maneuver

The Valsalva maneuver or Valsalva manoeuvre is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth and pinching one's nose shut...

.

• Voiced consonants include /v/, /z/, /ʒ/, /d͡ʒ/, /ð/, /b/, /d/, /ɡ/, /w/.
• Voiceless consonants include /f/, /s/, /ʃ/, /t͡ʃ/, /θ/, /p/, /t/, /k/, /ʍ/, and /h/.