Glottalic airstream

In phonetics, the airstream mechanism is the method by which airflow is created in the vocal tract. Along with phonation and articulation, it is one of three main components of speech production. The airstream mechanism is mandatory for sound production and constitutes the first part of this process, which is called initiation.

The organ generating the airstream is called the initiator and there are three initiators used in spoken human languages:

Though not used in any language, the cheeks may be used to generate the airstream (buccal mechanism, notated {ↀ} in VoQS). See buccal speech.

After a laryngectomy, the esophagus may be used as the initiator (notated {Œ} for simple esophageal speech and {Ю} for tracheo-esophageal speech in VoQS). See esophageal speech.

Percussive consonants are produced without any airstream mechanism.

Any of the three initiators − diaphragm, glottis or tongue − may act by either increasing or decreasing the pressure generating the airstream. These changes in pressure often correspond to outward and inward airflow, and are therefore termed egressive and ingressive.

Of these six resulting airstream mechanisms, four are found lexically around the world:

These mechanisms may be combined into airstream contours, such as clicks which release into ejectives.

The Khoisan languages have pulmonic, ejective, and click consonants, the Chadic languages have pulmonic, implosive, and ejective consonants, and the Nguni languages utilize all four, pulmonic, click, implosive, and ejective, in normal vocabulary. Most other languages utilize only one or two airstream mechanisms.

In interjections, the other two mechanisms may be employed. For example, in countries as diverse as Sweden, Turkey, and Togo, a pulmonic ingressive ("gasped" or "inhaled") vowel is used for back-channeling or to express agreement, and in France a lingual egressive (a "spurt") is used to express dismissal. The only language where such sounds are known to be contrastive in normal vocabulary is the extinct ritual language Damin (also the only language outside Africa with clicks); however, Damin appears to have been intentionally designed to differ from normal speech.

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