What exactly are Speech Sound Disorders?
Learn the signs, causes, and when to see a speech pathologist
Phonology, Articulation, and Motor Speech: What’s the Difference?
As a parent or guardian, hearing your child speak unclearly can be worrying, but understanding why they’re having trouble is the first step towards helping them achieve their goals. Speech sound delays and disorders can stem from different areas, including phonology, articulation, motor speech and structural problems, and therapy approaches can differ depending on which area the difficulty stems from.
Phonology: Understanding the Rules Behind Speech
Phonology refers to the system of rules our brains use to organise and produce speech sounds. Think of it as the "blueprint" your child’s brain follows to speak clearly and correctly. Some children are physically able to say certain sounds like “k” or “t” but may still replace or remove certain sounds in words. This is often due to a phonological difficulty, where the brain has mixed up the rules about which sounds should go where.
Children with phonological speech sound difficulties often use what are called phonological processes. These are patterns where sounds are simplified, swapped, or left out to make speech easier. For example, a child might say “tat” instead of “cat” by replacing the “k” sound with a “t” sound. Phonology therapy helps children re-learn sound patterns so they can say words more clearly and consistently.
Here are some common signs of phonological speech sound difficulties:
Mixing up sounds even though they can say them correctly on their own
Consistent sound errors like saying “gog” for “dog” or “tat” for “cat”
Leaving out sounds in words, such as saying “boon” instead of “spoon”
Replacing sounds with easier ones (e.g., “g” for “d” = “doe” for “go”)
Phonological error patterns are typical in early development, but when they persist beyond the expected age, they may need support from a speech pathologist.
Articulation: Learning How to Say the Sounds Clearly
Articulation refers to how our mouth muscles, like the lips, tongue, teeth, and jaw, work together to make specific speech sounds. Children with articulation difficulties know the rules for which sounds go in words, but they have trouble physically producing those sounds correctly. It’s like knowing exactly what you want to draw, but your pencil doesn’t quite follow your hand the way you need it to.
For example, a child may substitute the “s” sound by sandwiching their tongue between their teeth, saying “thun” instead of “sun.” This is typically known as a ‘lisp’ and can happen if they haven’t yet learned how to place their tongue correctly behind their teeth or control their breath for that sound.
Articulation difficulties often affect just one or two specific sounds, unlike phonological difficulties which follow broader patterns. Some articulation errors are part of normal development and will resolve with time. But if these errors persist beyond the age when most children have mastered the sound, it might be time to see a speech pathologist. Articulation therapy helps children practice and shape the correct movements to produce the target sound.
Motor Speech: Planning and Moving to Speak
Motor speech disorders affect a child’s ability to plan, coordinate, and carry out the precise movements needed for speech. These difficulties don’t come from a lack of understanding, as children with motor speech disorders often know exactly what they want to say. The challenge lies in the brain's ability to send the right messages to the mouth muscles (like the lips, tongue, and jaw) to produce those sounds smoothly and consistently.
A key sign of a motor speech difficulty is the inconsistent productions of words. For example, a child might say “banana” clearly one moment, and then struggle with it the next—saying “nana,” “buh-nana,” or getting stuck altogether. This variability is different from other types of speech sound difficulties where the errors tend to be more predictable and consistent.
There are different types of motor speech disorders. One common type is Childhood Apraxia of Speech (CAS), where the brain has difficulty planning the sequence of movements for speech. Another is dysarthria, where the muscles used for speech are weak or have reduced coordination.
Motor speech therapy is often intensive and highly repetitive, focusing on helping children practise the same words or sounds many times with support. Therapy may include visual cues, touch cues, and movement strategies to help the brain and mouth work better together over time.
Bottom line:
Phonology = The brain’s understanding of sound patterns
Articulation = The mouth’s ability to make sound production
Motor speech = The brain-to-muscle communication
Why It Matters
Understanding the difference between speech sound disorders can help families work with their speech pathologist to choose the right therapy approach. While all these areas can affect speech clarity, the cause is different, so the support needs to be tailored. Speech sound difficulties can also co-occur- so a child may have difficulty in areas of phonology AND articulation. If your child is working with a speech pathologist or you are about to begin therapy, ask them which area is being targeted and why. That knowledge can help you support therapy at home, too.
