this refers to sounds made with a secondary closure of the glottis
, in the larynx
. The qualification 'secondary' is significant. A sound made primarily by closing the glottis, such as an English h
or the glottal stop
of Hawaiian and of London English, is called glottal
(or even laryngal
, though these may be used differently)). The word 'glottalic' is used when the main blockage of the mouth is made elsewhere and the glottis is also used to affect the sound.
The glottis can be moved up or down. If the mouth cavity is closed off elsewhere, this means the trapped air is compressed or rarefied. Each possibility produces a different class of sound: with compression, the resultant sound when released is called ejective; with rarefaction, the resultant is called implosive. See under those terms for more details and examples.
The word 'glottalic' has also been used in the Glottalic Theory, a recent hypothesis in the study of proto-Indo-European (PIE), posited by Gamkrelidze and Ivanov, and of considerable interest to other linguists but not generally accepted. This says that where traditional studies of PIE assumed three classes of consonants, as t d dh, with the dh having breathy voice as in Sanskrit, in fact dh was really a normal d, and the sound traditionally reconstructed as d was an ejective or glottalic sound. This explains the rarity of b, since on the Gamkrelidze and Ivanov theory it would be an ejective p'. Across the world this sound as not as commonly met with as other ejectives.