Note: For the purposes of this discussion I am not going to include speech disorders such as fluency disorders (stuttering) and voice disorders (problems with the quality of the voice). I am going to focus on the speech disorders that affect articulation (how the speech sounds are produced).
Types of Speech Disorders
In order to understand what makes Childhood Apraxia of Speech unique, you first have to understand a little bit about the main types of speech disorders.
Articulation Disorder
A child has an articulation disorder when they have difficulty producing a specific sound correctly. Speech language pathologists see a lot of children who have trouble producing the /r/ sound, the /l/ sound, or the /s/ sound for example. The child may have trouble with more than one sound, but the difficulty is with the specific speech sound. They typically have trouble making the sound any time it comes up. So, you wouldn't typically see a child who can make a /s/ when it is at the beginning of the word, but can't when the /s/ is at the end of the word. To put it simply, an articulation disorder is a disorder at the level of specific sounds.
Usually this kind of problem doesn't impact intelligibility (how easily a stranger can understand them) too much and is relatively easy to treat in therapy. The therapist would work on helping the child learn to make the sound correctly first in isolation, and then at the beginning, middle, and ends of words. They would then move up to working on the sound in phrases, sentences,and eventually conversation. Articulation disorders respond well to being treated once or twice a week in small groups of children who are all working on the same sounds.
Phonological Disorder
A child has a phonological disorder when the speech errors they are making fall into patterns. Let me explain. Make a /k, k, k/ sound out loud. Now make a /g, g, g/ sound. Both of those sounds are made in the back of your mouth with the back of your tongue. Now make a /p, p, p/ sound and a /b, b, b/ sound. Both of those sounds are make in the front of the mouth with your lips pressed together. All of the consonant sounds in our language can be categorized by the place in the mouth in which they are produced and by how they are produced. Some sounds are front sounds and some sounds are back sounds. Some sounds are short and quick (/p/, /b/) while some sounds are long and drawn out (/m/, /sh/). Children with a phonological disorder have trouble with whole categories of sounds. They might take all back sounds and produce them in the front of the mouth so that words with /k/ and /g/ are pronounced with /t/ and /d/ instead. Or they might make a pattern of errors that has to do with syllable shape. They might leave off all consonants at the ends of words. In two syllable words they might always leave off the second syllable. You get the idea. A phonological disorder is not about having difficulty with a specific sound. It's a problem consistently demonstrated as a pattern.
To diagnose a phonological disorder a speech-language pathologist is going to analyze patterns of errors. The more patterns a child has difficulty with the harder they will be to understand. This type of disorder can significantly impact a child's intelligibility and is more difficult to remediate than a simple articulation problem. Children with a phonological order will typically be producing a lot of speech and will usually be able to imitate, they will just be difficult to understand. Their errors will be consistent.
When treating a child with a phonological disorder the speech-language pathologist will treat the patterns rather than specific sounds. The way the SLP structures therapy will be different than with a simple articulation problem and that difference is important if you are going to see the most improvement in the shortest amount of time. A phonological disorder is a significant speech disorder that takes a lot of therapy to address. You can address it in a group setting particularly if you group children together who are making errors with the same patterns.
Expressive Language Delay
I'm just going to touch on this briefly because this is another reason that a very young child might not be talking yet. Language is separated into two broad categories: receptive and expressive. Receptive language is how well you understand the language that you hear. Parents usually have a sense of whether their child understands what they're being told. For example, usually you'd expect a young child to follow simple directions like, "Get your baby." Expressive language is how well a child can formulate what they want to say. You might have a child of normal intelligence who understands everything they hear, seems to have a normal set of speech sounds based upon the sounds you hear when they babble or use the few words they do have, and yet is not expressing themselves normally for their age. In this case you would be seeing an expressive language delay.
Childhood Apraxia of Speech
Childhood Apraxia of Speech is distinct from other kinds of speech disorders. It is not a problem with a specific sound, groups of sounds, or patterns of production. Childhood Apraxia of Speech is a neurological motor planning disorder. The child knows what they want to say (therefore not expressive language delay). The speech structures and muscles are physically capable of making the sounds. The problem is in the planning of the muscle movements necessary to make the sounds and the transitions from one sound to the next.
This brings the scope of the problem to a whole different level. Now you aren't just trying to fix the /s/ sound. You're not even trying to teach a child who is moving all their back sounds to the front to make them in the correct place. You have to help a child learn to program all the sounds and sound combinations. This is a huge task because the way the muscles have to move to produce /ba/ is different than the way they have to move to produce /be/. So you can't just work on a generic /b/.
Because the problem is with motor planning, speech is often very difficult to understand and errors are inconsistent. Often children with Childhood Apraxia of speech are using smaller numbers of consonants and vowels than children with other types of speech disorders. They also tend to have better speech production in words and phrases that have become automatic (like uh, oh or bye, bye) than when trying to say something new. This makes sense because they've practiced the automatic phrases over and over so the motor planning for that specific word or phrase has been learned. These kids often have trouble imitating because they are being asked to produce something new on demand and they have trouble with the motor planning of anything new.
When treating a child with Childhood Apraxia of Speech or suspected Childhood Apraxia of Speech research has shown that the best results are obtained when therapy is intensive (several times a week) and individual (one-on-one). This is because the speech-language pathologist needs to get as many productions as possible during therapy and that is much harder in a group setting.
Academic Categories vs. Real Life Diagnoses
When you look at these four types of speech disorders on paper they seem very distinct and separate from each other. In real life, things are messier. Often a child's speech problem is due to a little bit of this and a little bit of that.
Also, with a very young child or an older child who isn't talking yet there just isn't enough speech to analyze. You can look for some
red flags that make you suspect one disorder is more likely than another, but you cannot be sure. The speech-language pathologist has to make an educated guess based on all the information and design the most appropriate treatment plan possible.
