A phonological process disorder involves patterns of sound errors. For example, substituting all sounds made in the back of the mouth like “k” and “g” for those in the front of the mouth like “t” and “d” (e.g., saying “tup” for “cup” or “das” for “gas”).

Another rule of speech is that some words start with two consonants, such as broken or spoon. When children don’t follow this rule and say only one of the sounds (“boken” for broken or “poon” for spoon), it is more difficult for the listener to understand the child. While it is common for young children learning speech to leave one of the sounds out of the word, it is not expected as a child gets older. If a child continues to demonstrate such cluster reduction, he or she may have a phonological process disorder.