View source for Glottis

===Phonation===
{{Main|Phonation}}
As the vocal cords vibrate, the resulting vibration produces a "buzzing" quality to the speech, called ''[[Voice (phonetics)|voice]]'' or ''voicing'' or ''pronunciation''.

Sound production that involves moving the vocal cords close together is called ''glottal''.<ref name=":0">{{Cite book|title=Introductory Phonology|last=Hayes|first=Bruce|publisher=Wiley-Blackwell|year=2009|isbn=978-1-4051-8411-3|url-access=registration|url=https://archive.org/details/introductoryphon00haye}}</ref> English has a [[Voiceless glottal fricative|voiceless glottal transition]] spelled "h". This sound is produced by keeping the vocal cords spread somewhat, resulting in non-turbulent airflow through the glottis.<ref name=":0" /> In many accents of English the [[glottal stop]] (made by pressing the cords together) is used as a variant [[allophone]] of the phoneme {{IPA|/t/}} (and in some dialects, occasionally of {{IPA|/k/}} and {{IPA|/p/}}); in some languages, this sound is a [[phoneme]] of its own. 

Skilled players of the Australian [[didgeridoo]] restrict their glottal opening in order to produce the full range of [[Timbre|timbres]] available on the instrument.<ref>{{cite journal |doi=10.1038/43639a |pmid=16001056 |title=Acoustics: The vocal tract and the sound of a didgeridoo |journal=Nature |volume=436 |issue=7047 |pages=39 |year=2005 |last1=Tarnopolsky |first1=Alex |last2=Fletcher |first2=Neville |last3=Hollenberg |first3=Lloyd |last4=Lange |first4=Benjamin |last5=Smith |first5=John |last6=Wolfe |first6=Joe |bibcode=2005Natur.436...39T |url=https://openresearch-repository.anu.edu.au/bitstream/1885/82233/8/01_Fletcher_Vocal_Tract_2005.pdf |hdl=1885/125584 |s2cid=4395889 |hdl-access=free }}</ref>

The vibration produced is an essential component of ''voiced'' [[consonant]]s as well as [[vowel]]s. If the vocal cords are drawn apart, air flows between them causing no vibration, as in the production of voiceless consonants.<ref>{{Cite journal |last=De'Ath |first=Leslie |date=2016 |title=Linguistics and Lyric Diction - A Personal Retrospective and a Selective Glossary |url=https://www.proquest.com/docview/1774332500 |journal=Journal of Singing |volume=72 |issue=4 |pages=465–474 |id={{ProQuest|1774332500}}}}</ref>

The glottis is also important in the [[Valsalva maneuver]].
* Voiced consonants include {{IPA|/v/, /z/, /ʒ/, /d͡ʒ/, /ð/, /b/, /d/, /ɡ/, /w/.}}
* Voiceless consonants include {{IPA|/f/, /s/, /ʃ/, /t͡ʃ/, /θ/, /p/, /t/, /k/, /ʍ/, and /h/.}}