Articulation refers to how a speaker shapes air from the lungs to produce speech sounds. Speech is made up of a variety of consonant and vowel sounds, and each of these is a phoneme. A phoneme is the smallest unit in a language that can differentiate one word from another, and while English phonemes don’t exactly map onto English letters, they are pretty close. For example, the /s/ sound is represented by the letter “s” and sometimes “c.” The /k/ sound is almost always spelled with “k”, except for /kw/ combinations, which we spell with “qu.” And, did you know there are two “th” sounds in English? If you say “thigh” and “thy” you’ll notice the difference.
Children develop the phonology of their language starting from birth until they’re in the early school age years. While there’s variation in when kids master certain sounds, by and large we expect them to have adult-like speech by the time they’re about 8 years old. If kids are older than age 8 and still have speech errors, we call this a persistent speech sound disorder, and these kids would benefit from speech therapy services, if they’re not already enrolled.
Consonant development starts when kids are around 4 to 6 months old—really still babies, not even kids! Early consonants include /m/ and /b/, and kids demonstrate ability to make these sounds when they babble in sequences like “bababa” and “mamama.”
By the time they’re 1 year old, we like to see that babies are developing a range of consonant sounds, including /b/, /d/, /g/, /m/, /n/, /p/, /t/, /w/, “y” and maybe /k/. This gives them a nice set of building blocks to start making first words with.
From age 1 to 4, we see growth and learning of more consonant sounds. /f/, /v/, /s/, /z/, “sh,” “ch,” and “l” likely start emerging, although it’s very typical to make some mistakes on these sounds early on. Common errors include substituting a /b/ for /f/ and /v/, or a /d/ or “th” for /s/ and /z/. Many children produce the /k/ or /g/ sound as /t/ or /d/. At the same time, making an /s/ for “sh” or “ch” can be frequent until a child reaches age 4 or 5. Another common error is substituting the /w/ for /r/ or /l/ sound. These errors are called “substitution” errors because the child replaces the target sound with another.
Sounds like /s/ and /z/ may also be “distorted,” typically by being a little less precise or “sharp,” until age 6 or 7, especially as teeth are growing and falling out. /r/ sometimes is produced with reduced tension, but not fully substituted with a /w/. These types of errors can be common in the early school years for kids. We don’t expect to see substitution errors persist for as long as some of these mild distortions, and typically many substitution errors can have a greater negative impact on a child’s ability to be understood. Because of this, a child with frequent substitution errors may start therapy sooner, while a child with distortion errors may be monitored to see if they outgrow the difference.
There are also less typical types of errors that kids sometimes make. Unusual errors, like substituting a /k/ for a /t/ sound, occur less frequently as a developmental type of error, and are more commonly seen in children with underlying speech and language issues. For this reason, we may start treatment as soon as this type of error is identified.
Much of the decision about when to intervene is based on a combination of the child’s age, which sounds are in error, what the error is, and whether there is a functional impact on the child’s ability to be understood. The child’s age and type of error largely impacts our expectation that the child may simply outgrow a common speech developmental error. For example, we don’t usually recommend treating a /w/ for /r/ substitution when a child is 3—many 3 year olds make this error! However, we would recommend treating a /w/ for /r/ when a child is 8—perhaps even as early as 6 or 7. If a child who’s missing their front teeth is producing /s/ as “th” at age 6 gets evaluated, we would probably hold off on treating this error. Similarly, if a child is two and produces /t/ for /s/, we consider that a common error for a two year old. However, if a child is two and produces a nasal fricative for /s/, which is an atypically snort of air through the nose to mark the /s/, then we would start therapy to treat the error. Talking with an SLP is the best way to determine what your child’s error is and whether it’s something they’re likely to grow out of, or need therapy to address! Check out our “how to teach” series to see if any of the tips help you, or sign up for a screening or evaluation today!