Question
What speech sounds would be affected by poor velopharyngeal closure and what would they sound like instead?
Answer
The speech sounds affected by poor velopharyngeal closure (otherwise called velopharyngeal inadequacy or VPI), include any sound where there is a need to build up intraoral air pressure. For example, stops such as 'p, b, t, d, k, and g' all require intraoral air pressure to be built up by closing the velopharyngeal (VP) port and obstructing the vocal tract and then releasing of the obstruction (e.g., lips closing then opening for 'p' or 'b'). Similarly, fricatives, such as 's, z, sh, zh, th, f, and v' require the VP port to be closed while air is forced through a constriction in the oral portion of the vocal tract. When a person has VPI, much of the air pressure, and thus acoustic energy will go through the nose instead of the mouth. Thus, the person may sound hypernasal with nasal air emissions, especially on high pressure oral consonants. In addition, vowels may sound nasalized. However, the nasals, 'm, n, and ng' will sound fine, since there supposed to be produced with the VP port open.
Some children with VPI secondary to cleft palate will come up with maladaptive compensatory strategies such as valving the airstream below the level of the VP port, thus avoiding the escape of air through the VP mechanism and nose. These strategies may include producing a pharyngeal fricative or affricate for fricatives and affricates and glottal or pharyngeal stops for all stops. Some children learn that they can get around building up intraoral air pressure for a 'p' and will simply produce one by popping their lips (static 'p') versus building up oral air pressure. For these children it will be very important to teach the correct placement and manner of articulation.
In observing my own son, now 2