Functional and anatomical relationships in nasality

Normally, the soft palate reaches the posterior pharyngeal wall during production of sibilant and plosive sounds (solid arrow, top diagram). With other sounds, the passage is open enough for normal nasal resonance (dashed arrow, top diagram). Large adenoids (bottom left diagram) interfere with airflow and produce hyponasality. Velopharyngeal insufficiency, as in submucous cleft, lets sound escape through the nose and produces hypernasality (bottom right diagram).