Narrow and closed at rest, it opens during swallowing and yawning, controlled by the tensor veli palatini and the levator veli palatini (muscles of the soft palate). Children with a cleft palate have difficulties controlling these muscles and thus are unable to open the Eustachian tube. Secretions accumulate in the middle ear when the tube remains dysfunctional over a long period of time, which cause hearing loss and middle ear infections. Ultimately, hearing loss can lead to impaired speech and language development. Causes
The general term for disorders of the velopharyngeal valve is velopharyngeal dysfunction (VPD). It includes three subterms: velopharyngeal insufficiency, velopharyngeal inadequacy, and velopharyngeal mislearning. Velopharyngeal insufficiency can be caused by an anatomical abnormality of the throat. It occurs in children with a history of cleft palate or submucous cleft, who have short or otherwise abnormal vela. Velopharyngeal insufficiency can also occur after adenoidectomy. Velopharyngeal incompetence is a defective closure of the velopharyngeal valve due to its lack of speed and precision. It is caused by a neurologic disorder or injury (e.g. cerebral palsy or traumatic brain injury). Sometimes children present no abnormalities yet still have hypernasal speech: this can be due to velopharyngeal mislearning, indicating that the child has been imitating or has never learned how to use the valve correctly. Diagnosis
There are several methods for diagnosing hypernasality. A speech therapist listens to and records the child while analysing perceptual speech. In hypernasality, the child cannot produce oral sounds (vowels and consonants) correctly. Only the nasal sounds can be correctly produced.
Without the use of a technological aid, nasal emission is sometimes judged by listening for any turbulence that may be produced by the nasal airflow, as when there is a small velopharyngeal opening and there is some degree of mucous in the opening. More directly, methods recommended include looking for the fogging of a mirror held near the nares or listening through a tube, the other end of which is held in or near a nares opening.There have been many attempts to use technological augmentation more than a mirror or tube to aid the speech pathologist or provide meaningful feedback to the person attempting to correct their hypernasality. Among the more successful of these attempts, the incompleteness of velopharyngeal closure during vowels and sonorants that causes nasal resonance can be estimated and displayed for evaluation or biofeedback in speech training through the nasalance of the voice, with nasalance defined as a ratio of acoustic energy at the nostrils to that at the mouth, with some form of acoustic separation present between the mouth and nose. In the nasalance measurement system sold by WEVOSYS, the acoustic separation is provided by a mask-tube system, nasalance measurement system sold by Kay-Pentax, the acoustic separation is provided by a solid flat partition held against the upper lip, while in the system sold by Glottal Enterprises the acoustic separation can be by either a solid flat partition or a two-chamber mask.However, devices for measuring nasalance do not measure nasal emission during pressure consonants.