The glottal lips open partly by yielding sidewise,—that is, they are compressed,—and partly by being shoved upward and outward.
The glottal lips vibrate differently for the different vowels.
In standard English the h is a glottal continuant only when there is precise and emphatic utterance.
The backward apostrophe probably represents the glottal stop; the simple apostrophe may indicate the same sound.
The language was rich in glottal stops, clicks and guttural strangling sounds.
glottal glot·tal (glŏt'l)
Of or relating to the glottis.