Hyponasality refers to a reduction in nasal resonance due to blocking of the nasal airway. Denasality refers to complete blockage of the nasopharynx, when no air can enter the nasal passage from the posterior pharyngeal area. Mixed nasality occurs in patients with VPI who evidence increased nasal resistance, where some sound is resonated in the nasal airway but not enough for nasal consonants to retain their integrity. The speech associated with it is muffled. It is caused by an intranasal obstruction.
Articulation can often be the most significant communication disorder associated with cleft palate.
As a group, patients with CP show marked variability in their articulatory abilities. Audible nasal emission is the noise that is heard when air passes through the nasal cavity. If there is marked intranasal resistance to air flow, nasal turbulence will occur, which is a severe form of audible nasal emission. Hypernasality and nasal emission are obligatory consequences of an un-operated cleft palate or faulty VP mechanism. Mis-articulation patterns, however, are compensatory , that is, they are learned.