The document discusses different aspects of airstream mechanisms in speech production. It describes three main types of airstream mechanisms: pulmonic, glottalic, and lingual/velaric initiation. Pulmonic initiation uses the lungs to push air out (egressive) or pull air in (ingressive). Most sounds are egressive pulmonic. Glottalic initiation uses the glottis to eject (egressive) or implode (ingressive) air. Lingual initiation uses the tongue and velum to create clicks by pulling air in. It provides examples of sounds that use each mechanism and discusses their place and manner of articulation.