A hearing test is also desirable. A mirror is held beneath the nose while the child pronounces the vowels. Nasal air escape, and thus hypernasality, is indicated if the mirror fogs up. A pressure-flow technique is used to measure velopharyngeal orifice area during the speech. The patient must be at least three to four years old. A video nasopharyngeal endoscopy observes velopharyngeal function, movements of the soft palate, and pharyngeal walls. It utilises a very small scope placed in the back of the nasal cavity. The doctor will then ask the child to say a few words. The patient must be at least three to four years old to ensure cooperation. A cinefluoroscopy gives dynamic visualisation and can easier be applied to younger children, though it has the disadvantage of exposing the patient to radiation. A nasometer calculates the ratio of nasality. The patient wears a headset, where the oral and nasal cavities are separated by a plate. On both sides of the plate are microphones. The ratio calculated by the nasometer indicates the amount of nasality, with a higher ratio indicating more nasality. Effects on Speech
Hypernasality is generally segmented into so-called resonance effects in vowels and some voiced or sonorant consonants and the effects of excess nasal airflow during those consonants requiring a buildup of oral air pressure, such as stop consonants (as /p/) or sibilants (as /s/). The latter nasal airflow problem is termed nasal emission, and acts to prevent the buildup of air pressure and thus prevent the normal production of the consonant.
Hereditary progressive mucinous histiocytosis is a very rare, benign, non-Langerhans cell histiocytosis. An autosomal dominant or X-linked hereditary disease described on the skin, it has been found almost exclusively in women. One case of the disease in a male patient has been reported. See also
Non-X histiocytosis

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