Hypernasal speech
| Hypernasality | |
|---|---|
| Classification and external resources | |
| ICD-10 | R49.21 |
| ICD-9-CM | 784.43 |
| MeSH | D014833 |
| Snoring | |
|---|---|
| Sound sample of snoring | |
| Classification and external resources | |
| ICD-10 | R06.5 |
| ICD-9-CM | 786.09 |
| DiseasesDB | 12260 |
| MeSH | D012913 |
Hypernasal speech (also hyperrhinolalia or open nasality; medically known as Rhinolalia aperta from Latin rhinolalia: "nasal speech" and aperta: "open") is a disorder that causes abnormal resonance in a human's voice due to increased airflow through the nose during speech. It is caused by an open nasal cavity resulting from an incomplete closure of the soft palate and/or velopharyngeal sphincter. In normal speech, nasality is referred to as nasalization and is a linguistic category that can apply to vowels or consonants in a specific language. The primary underlying physical variable determining the degree of nasality in normal speech is the opening and closing of a velopharyngeal passageway between the oral vocal tract and the nasal vocal tract. In the normal vocal tract anatomy, this opening is controlled by lowering and raising the velum or soft palate, to open or close, respectively, the velopharyngeal passageway.
The palate comprises two parts, the hard palate (palatum durum) and the soft palate (palatum molle), which is connected to the uvula. The movements of the soft palate and the uvula are made possible by the velopharyngeal sphincter. During speech or swallowing, the uvula lifts against the back throat wall to close the nasal cavity. When producing nasal consonants (such as "m", "n", and "ng"), the uvula remains relaxed, thereby enabling the air to go through the nose.
The Eustachian tube, which opens near the velopharyngeal sphincter, connects the middle ear and nasal pharynx. Normally, the tube ensures aeration and drainage (of secretions) of the middle ear. 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.
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