Many parents who start researching speech disorders have questions about the differences in apraxia, or motor planning difficulties, as compared to a phonological disorder. “They sound the same to me,” is what many parents tell me. Actually many professionals have questions too! This is a common debate during the diagnostic process for many clinicians. First, I’ll provide a brief overview of both disorders, then I’ll give you my clinical opinion.
Apraxia is a neurological speech disorder that affects a child’s ability to plan, execute, and sequence the movements of the mouth necessary for intelligible speech. Apraxia can also be referred to as developmental verbal apraxia, childhood apraxia of speech, or verbal dyspraxia. Most SLPs use the terms interchangeably. Characteristics of apraxia include:
- Limited babbling is present in infancy. These are quiet babies.
- Few or no words when other babies are talking by age 2
- Poor ability to imitate sounds and words
- Child substitutes and/or omits vowel and consonant sounds in words. Errors with vowel sounds are not common with other speech disorders.
- His word attempts are “off-target” and may not be understood even by parents.
- He may use a sound such as “da” for everything.
- Often his errors are inconsistent, or he may be able to say a word once and then never again. The child understands much more than he can say.
- There is sometimes (but not always) a family history of communication difficulty. (i.e. “All the boys in our family talk late,” or “My husband’s grandfather still has trouble pronouncing some hard words.”)
A phonological disorder is difficulty with the “rules” or “patterns” for combining sounds intelligibly in speech in English. For example, phonological processes patterns include prevocalic consonant deletion (leaving off consonant sounds that precede a vowel such as “at” for hat), syllable reduction (producing only one syllable in a multisyllabic word such as “bay” for baby), or reduplication (simplifying a multisyllabic word to a duplicated pattern such as saying “bubu” for bubble or even “dog dog” for doggie).
There are many patterns for analyzing a child’s speech according to a phonological processes model. All of these processes are common in typically developing children as well. It becomes a problem when most children are maturing in their patterns of production, and a child is not. For example, final consonant deletion (leaving off ending consonant sounds in words) typically disappears between 2 1/2 to 3 years of age. If a child is not including final consonants by this age, it would be considered “disordered” or “atypical” since most of his same-age peers are now using a more mature pattern.
A child with only a phonological disorder exhibits typically developing language, meaning that his vocabulary and utterance length are the same as his peers, but he continues to exhibit patterns that are consistent with a younger child’s speech errors.
Important Diagnostic Differences
1. Vowel Sounds- Indicators for me always include a child’s vowel sounds. Both children with apraxia and phonological disorders make errors with consonant sounds. Children with apraxia also substitute, or in some cases omit, vowel sounds too. For the most part, children with a phonological disorder use consistently accurate vowel sounds. (Remember that vowels are A, E, I, O, U, and sometimes Y. Consonants are the other remaining letters of the alphabet.)
2. Consistency in Errors - Children with phonological disorders are generally consistent with their errors. This means that if they mess up a word, they usually mess it up all or most of the time, and usually in the same manner (until they start learning new pattern in therapy, and then they will likely revert between their “old” way of saying a word and their “new” way.)
Children with apraxia are very inconsistent. This means that they may say a word correctly once, and say it incorrectly a minute later. Words may be so “off-target” that the intended word is unrecognizable. For minimally verbal apraxic children, they may say the word once, and then you may not hear it again for a long time.
Children with a phonological disorder exhibit patterns with errors. For example, a child may omit final consonant sounds all of the time. A child with apraxia may include a final consonant sound in one word, but not be able to produce the same final consonant sound in the same word or the same sound in another word.
3. Language Skills- Children with apraxia almost always have delayed expressive language skills (especially before therapy starts.) They do not have the same vocabulary size and utterance length as children their age.
Children with a phonological disorder may have expressive language skills within or closer to the normal range. They use lots of words and try to combine them into phrases like their same-age peers, but you may not be able to understand very much. (This is different than jargon, or “baby talk.” Children with a phonological disorder are saying real words, but they substitute or leave off so many consonant sounds that you don’t know what they are saying.)
4. Other Characteristics while Speaking- Children with apraxia often look like they are “groping” for words. Things parents say to describe this include:
- “He sometimes opens his mouth to talk, but then it looks like he forgot what he was going to say.”
- “She doesn’t know what to do with her tongue when she talks.”
- “I see him watching my mouth closely, and he tries to move his mouth in funny ways to copy mine, but he can’t.”
Children with phonological disorders do not have these issues. For the most part, they can and do try to repeat what you’ve said to them without the hesitations.
5. Verbal Imitative Abilities- Children with apraxia have major difficulties imitating or repeating what you’ve said (especially before therapy begins). Children with a phonological disorder can repeat you, but the word may not be accurate.
6. Oral Imitative Abilities- Children with apraxia have difficulties with using their mouths to talk or to imitate or perform certain movements on request , but not in other activities like eating or if the activity is “automatic.” For example:
- “He can stick his tongue out when he’s licking a sucker, but he can’t do it when I show him.”
- “She blew out her birthday candles last week. I don’t understand why she won’t blow for you.”
Children with phonological disorders are more consistent with what they can and can’t do with their mouths.
Hopefully this helped sort out some of the questions for you. I hope it doesn’t leave you more confused! Be sure to discuss these things with your child’s speech-language pathologist. He or she should be able to give you good reasons why or why not he/she believes a diagnosis is or isn’t appropriate for your child.