Young children mix up sounds all the time. "Wabbit" for "rabbit" and "nana" for "banana" are familiar examples.[3] But if your child is often hard to understand, or if friends and teachers regularly ask you to translate, you may start hearing terms like "articulation" and "phonological." This guide explains what each one means, what typical sound development looks like, and when it's reasonable to ask for an evaluation.
What is a speech sound disorder?
"Speech sound disorder" is the umbrella term. The American Speech-Language-Hearing Association (ASHA) uses it for "any difficulty or a combination of difficulties with perception, motor production, or phonological representation of speech sounds and speech segments."[1] Some speech sound disorders have a known cause, such as hearing loss, a cleft palate, or a motor speech disorder like childhood apraxia of speech.[1] Many others have no known cause; ASHA notes these were "historically called 'articulation and phonological disorders.'"[1]
Speech is different from language. NIDCD describes speech as talking, which involves precisely coordinated movements of the tongue, lips, jaw, and vocal tract, and language as the shared rules people use to express ideas.[4] So a child can have plenty of words and ideas and still be hard to understand because of how they produce sounds. If you're sorting out those two areas, our post on receptive vs. expressive language covers the language side.
What's the difference between articulation and phonological disorders?
ASHA describes these as "disorders of the motor production of speech sounds and the linguistic aspects of speech production," referred to as "articulation and phonological disorders, respectively."[1] In everyday terms:
- Articulation is about the physical movements of making a sound. A child may have trouble producing particular sounds, and ASHA's examples of error types include distortions, where "sounds are altered or changed (e.g., a lateral /s/)."[1]
- Phonological refers to the sound system of a language, and the patterns a child uses to simplify it. ASHA describes phonological patterns as "systematic sound changes or simplifications that affect a class of sounds (e.g., fricatives), sound combinations (e.g., consonant clusters), or syllable structures."[1] For example, a child who says "tat" for "cat" and "date" for "gate" may be replacing back-of-the-mouth sounds with front-of-the-mouth sounds across many words.[2]
In real life the line isn't always sharp. ASHA notes that "it is often difficult to clearly differentiate between articulation and phonological errors," and that "a single child might show both articulation and phonological error types."[1] That's one reason the distinction is made by a speech-language pathologist (SLP) during an evaluation rather than from a single mispronounced word.
Common speech sound patterns in young children
ASHA notes that children "often demonstrate 'typical' errors and phonological patterns" while they learn.[1] ASHA's resource on selected phonological patterns lists examples, along with the approximate ages by which they are typically eliminated:[2]
| Pattern | What happens | Example | Typically gone by about |
|---|---|---|---|
| Final consonant deletion | The last consonant in a word is dropped | "bu" for "bus" | 3 years |
| Fronting | A sound made in the back of the mouth is replaced with one made in the front | "tat" for "cat" | 4 years |
| Weak syllable deletion | An unstressed syllable is left out | "nana" for "banana" | 4 years |
| Cluster reduction | Two consonants together are simplified to one | "top" for "stop" | 4 years (5 years for clusters with /s/) |
| Stopping | A sound like /f/ or /s/ is replaced with a "stop" sound like /p/ or /t/ | "pun" for "fun" | 3 to 5 years, depending on the sound |
| Gliding | /r/ or /l/ is replaced with /w/ or /y/ | "wabbit" for "rabbit" | 6 to 7 years |
ASHA also notes that "children usually acquire most speech sounds by age 5."[2] Some sounds come later. NIDCD's checklist for 4 to 5 years says a child "says most sounds correctly except for a few (l, s, r, v, z, ch, sh, and th)."[4]
Development also depends on the language or dialect a child is learning. ASHA explains that SLPs analyze "whether those patterns are typical within the child's linguistic community."[1] A pronunciation that matches a child's home language or dialect is a difference, not a disorder.
How clear should my child's speech be?
Parents often wonder about this, and there's no single cutoff. ASHA summarizes two studies:[1]
- Using parents' estimates of how well their child was understood by others, one study (Coplan and Gleason, 1988) reported expected intelligibility of about 50% at 22 months, 75% at 37 months, and 100% at 47 months.
- A more recent study (Hustad and colleagues, 2021) measured how well unfamiliar listeners understood single words spoken by children without speech sound disorders. On average, children reached about 50% at 31 months, 75% at 49 months, and 90% at 83 months.
The CDC's milestone checklist for 3 years includes "talks well enough for others to understand, most of the time."[5] NIDCD's checklist for 2 to 3 years includes speaking "in a way that is understood by family members and friends."[4] ASHA also notes that intelligibility "can vary depending on context and the familiarity of listeners," which is worth keeping in mind if you mostly hear your child at home.[1]
Signs it may be time to ask a speech-language pathologist
ASHA lists these among the common signs of speech sound disorders:[1]
- Omissions: leaving sounds out, like "cuh" for "cup"
- Substitutions: swapping one sound for another, like "wabbit" for "rabbit"
- Additions: adding an extra sound, like "buh-lack" for "black"
- Distortions: sounds that come out altered, like a lateral /s/
- Syllable errors: dropping weak syllables, like "tefone" for "telephone"
- Inconsistent productions: saying the same word differently each time
Many of these are expected at younger ages.[1] If patterns seem to be continuing past the ages in the table above, or you're simply unsure, the Communication Health Support Association (CHSA) advises: "If you're concerned about your child's speech development, consult a speech-language pathologist (SLP)."[3]
ASHA also describes factors linked with a higher likelihood of speech sound disorders, including being male, pre- and perinatal problems such as preterm delivery or low birthweight, a family history of speech or language difficulties, and persistent middle ear fluid (otitis media with effusion), which is often associated with hearing loss.[1] CHSA recommends a hearing evaluation to rule out hearing loss as a factor.[3]
Why the difference matters
Sorting out the type of errors helps guide what comes next. ASHA notes that a child's specific errors "might need different treatment approaches," and that treatment selection depends on factors including the child's age, the type of speech sound errors, severity, and how much the errors affect intelligibility.[1] ASHA also cites an estimate that 40% of children with speech sound disorders had a co-occurring language impairment, which is why an evaluation usually looks at language as well as speech.[1]
Speech sound disorders are common in young children, though estimates vary widely. ASHA reports estimates of 2.1% to 23% for 4- to 6-year-olds, and 3.6% for persistent speech sound disorders at age 8.[1] If you'd like to know more about what an evaluation involves, see our pages on speech and language evaluations and speech therapy.
The bottom line
Articulation difficulties involve the physical production of particular sounds; phonological difficulties involve patterns that affect groups of sounds. Many children show both, and many sound errors are a normal part of learning to talk. If your child is often hard to understand, or certain patterns are hanging on longer than you expected, talking with a speech-language pathologist can help you learn whether what you're hearing is typical for your child's age and language.
Sources
- American Speech-Language-Hearing Association (n.d.). Speech Sound Disorders: Articulation and Phonology (Practice Portal). ASHA.
- American Speech-Language-Hearing Association (n.d.). Selected Phonological Patterns. ASHA Practice Portal.
- Communication Health Support Association (n.d.). Speech Sound Disorders. CHSA (HelpingYouCommunicate.org).
- National Institute on Deafness and Other Communication Disorders (n.d.). Speech and Language Developmental Milestones. NIDCD, National Institutes of Health.
- Centers for Disease Control and Prevention (n.d.). Milestones by 3 Years. CDC, Learn the Signs. Act Early..
Articles from Speech Me Therapy, a pediatric speech-language therapy practice in North Phoenix serving Scottsdale, Paradise Valley, and families across Arizona by telehealth. Our posts summarize published guidance from professional and public health organizations; sources are listed at the end of every article.