The manner of articulation is the configuration and interaction of the articulators when producing a [[speech signal]]. A parameter of manner is called stricture depending on how much the airflow is blocked by the articulators. From greatest to least stricture, speech sounds can be classified as: - [[stop consonant]] when an occlusion occurs, blocking the airflow; - [[fricative consonant]] when there is a constriction that produces a strong turbulent airflow; - [[semi-vowel]] when there is only slight turbulence; - [[vowel sound]] unimpeded airflow; Some authors include additional manners of articulation - [[lateral consonant]] when the air flows along one or both of the sides of the tongue; - [[nasalization]] the production of a sound while the velum is lowered letting the airflow pass through the nasal cavity.