:Airstream mechanism:

The manner in which an airstream is set in motion for the purposes of speech. Airstream mechanisms may produce ingressive (inward) or egressive (outward) airflow. An airstream mechanism consists of the movement of an initiator. Speech sounds are produced with one of three airstream mechanisms, or occasionally by a combination of two of these. The mechanisms are:

Name Initiator Egressive Ingressive
Pulmonic lungs most speech sounds  
Glottalic/Pharyngeal closed glottis ejectives voiceless implosives
Velaric/Oral velar closure   clicks
Velaric + Pulmonic     voiced clicks
Pulmonic + Glottalic     voiced implosives