A glottalic consonant is a consonant produced with some important contribution (a movement, a closure) of the glottis (the opening that leads from the nose and mouth cavities into the larynx and the lungs).

Glottalic sounds can be either egressive or ingressive. Egressive glottalics are also called ejectives, while ingressive glottalics are known as implosives. Ejectives are almost always voiceless stops (plosives), while implosives are almost always voiced stops.

How to produce an ejective consonant

In order to produce, for example, an ejective p, do as follows:

1. Get some breath!
2. Close lips together so as to pronounce /p/.
3. Close the glottis (like you do spontaneously just before a word that starts with a vowel, when pronounced in isolation–i.e. air must not flow from your lungs.
4. Let out some air, releasing both closures (labial and glottal) at the same time. The sound should be clicky and dull.

The same principle applies to any ejective consonant, substituting the appropriate place of articulation (alveolar ridge, velum, etc.) for the lips.

How to produce an implosive consonant

In order to produce an implosive b, do as follows:

1. Close lips together so to as pronounce /b/.
2. Close the glottis (see above).
3. The glottis moves up and down when swallowing If you're a male, you should be able to feel it with your hand on your throat–your Adam's apple shows the movement. With some practice you can move the glottis down at will. Once you can do that, go on:
4. Move your glottis down without opening your lips. This will cause a negative pressure inside your mouth cavity. Once this pressure is achieved, release your labial closure and let air into your mouth and lungs. It should be a deep hollow sound.

The same principle applies for other implosive consonants, only with the front closure produced elsewhere (for example, at the velum for implosive g).

Glottalic sounds in real world languages

Most of the major languages in the world do not have glottalic sounds. A number of Caucasian languages, as well as Native American languages, and many others, feature ejectives (as well as other forms of glottalization, pharyngealization, etc.).

Implosives are even rarer. They, like clicks (velaric ingressive consonants), are mostly confined to certain very specific African languages.