The lips may be used to constrict the front of oral cavity, and to alter the shape and length of the oral cavity. Vowels have minimal oral cavity constriction and are typically voiced. The property of sounds that, in their normal articulation, involve spontaneous phonation, is termed sonorance . Vowels and nasal consonants are sonorant. The point of articulation is the position of maximum constriction in the oral cavity.
Point of articulation is given by naming the lower and the upper articulators .
English Consonant Points of Articulation Manner of Articulation Manner of articulation refers to the degree of constriction in the oral cavity. Obstruent consonants are made with closure sufficient to preclude spontaneous voicing. Sonorant consonants have a vocal track open sufficiently to sustain spontaneous voicing. A stop has a closed oral cavity. A fricative involves a narrow oral opening that results in turbulent airflow.