Speech Sounds by Age: When Each One Should Arrive

Which sounds arrive when

A review of fifteen studies covering 18,907 children speaking English in the United States produced the clearest picture available of when each consonant turns up. Grouped by the age at which most children have it:

The voiceless th in thumb comes last of all, around six. Grouped a different way: the plosives, nasals and glides are finished before four, the affricates around five, the liquids around six, and the fricatives last.

Which means that a four-year-old saying wabbit is on schedule, not behind. A five-year-old saying fumb for thumb is on schedule. Two of the sounds adults correct most often are the two that arrive last, and correcting them early achieves nothing except making a child self-conscious about their own mouth.

How much a stranger should understand

This is the more useful measure, because it is the one that affects a child’s life. Sounds are a detail. Being understood is the point.

Research tracking intelligibility from thirty months onwards found that the average three-year-old was understood about half the time by listeners who did not know them, for single words and for sentences alike. At thirty months the spread between children was enormous, running from under a fifth of speech understood at the low end to roughly three quarters at the high end. Full intelligibility arrives considerably later than the old rule of thumb suggests, and the climb continues well into the school years.

Two things follow from that. The first is that a three-year-old who is hard work to follow is extremely common and usually not a problem. The second is that by four or five, a typically developing child is generally intelligible even to strangers, so a five-year-old whom the neighbours cannot follow is a different situation and worth measuring rather than waiting out.

Two languages

In Miami this changes the picture for most families. Spanish and English do not share a sound system: English has sounds Spanish does not use at all, and Spanish has the trilled rr, which is one of its latest-arriving sounds. A child building both is working through two schedules, and the overlap between them is imperfect.

An accent carried from one language into the other is a difference, not a disorder, and it is not something therapy sets out to remove. What matters is whether the child is behind in both languages. A child on track in Spanish and finding English hard is doing what bilingual children do. A child behind in both is the one to look at. That distinction, and why dropping a home language is the wrong response, is covered in bilingualism and speech delay.

Patterns that matter more than single sounds

Speech-language pathologists pay less attention to individual sounds than parents expect, and more to the shape of the errors.

• Everything made at the front, or everything at the back. Tat for cat, or gog for dog, past the age where the sound should be available.
• Whole syllables disappearing. Nana for banana at four.
• Inconsistency on the same word. The same word produced three different ways in one conversation is a distinctive pattern and worth flagging.
• Air escaping through the nose, or speech that sounds persistently nasal.
• Vowels that are off, not only consonants. This is less common and gets noticed less.

Worth asking about if: your child had words and has lost them; people outside the family cannot follow them at three; your child is frustrated, gives up, or has stopped trying to talk to strangers; speech became suddenly harder to understand; there is a history of repeated ear infections or glue ear; or you have ever wondered about their hearing. Hearing is checked first, always, because it is the cheapest thing to rule out and the most consequential to miss.

There is one further reason not to leave it. Children with a preschool history of speech sound difficulties are around two and a half times more likely to meet criteria for a reading disorder later. That is a raised risk rather than a forecast, and it is the main argument for measuring rather than waiting.

When to ask

A speech evaluation is a measurement. Sounds are sampled in single words and in connected speech, intelligibility is judged by someone who does not know your child, the mouth and its movements are looked at, and comprehension is tested alongside production, because speech difficulties and language difficulties travel together more often than not. What the appointment involves is set out in what a speech evaluation looks like.

Most of these evaluations end with a range of normal and a date to review. That is a good outcome, and it is worth the appointment to get it.

Questions parents ask