Clefts affect the soft palate, which is the posterior part of the roof of the mouth. If you move your tongue along the roof of your mouth from front to back, you will notice the roof of your mouth becomes soft as you move your tongue towards the back. The soft palate moves when we speak, to prevent air from escaping into your nose and causing a hypernasal quality. When that happens, it becomes difficult for the child to produce many of the speech sounds in English. Most of the speech sounds in English require that the space between your mouth and your nose behind the soft palate be completely closed. The only exceptions are the sounds M N and the sound at the end of ING. Those are the only three nasal sounds in English. All other sounds are oral sounds and require that the space between the nose and the mouth be closed by the soft palate. Children who have clefts are frequently unable to get complete closure of that space. As a result, they have abnormal speech.
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