Speech Sound Library

Every speech sound, by age

Speech sounds don't all arrive at once. They develop in a predictable order over several years, so a 3-year-old is supposed to still be missing several of them. This library lays out the 23 consonant and digraph sounds Sound Safari covers: when each one typically develops, the errors that are normal along the way, how to practice it, and the complete word list to work from. Whether you're a parent checking if “wabbit” is still on schedule or an SLP building a target list, each sound opens to its full guide. The developmental ages come from McLeod & Crowe (2018) and Crowe & McLeod (2020), the same norms speech-language pathologists use, and the word lists come from Sound Safari's own practice library.

What 50% and 90% mastery mean

Every bar in the chart above spans two ages — a 50% mastery i Here, mastery means producing the sound correctly on a single-word test — not necessarily in every word in fast conversation. age and a 90% mastery age — and the gap between them is the point. The 50% age is when about half of children produce the sound correctly, so it's just emerging: showing up in some kids but not most. The 90% age is when nine in ten children have it — the “should be solid by now” point, and the one speech-language pathologists actually watch.

Showing both ages is what lets you tell a sound that's simply still developing from one that's genuinely behind. Being a little past a 50% age is common and usually typical. It's a sound still missing or substituted well past its 90% age — especially if a child is hard to understand or frustrated by their own speech — that's a good reason to talk to an SLP.

Browse by mastery age

Pick a sound to open its full guide — developmental norms, common challenges, how to practice, and the full word list by position.

Minimal pairs word lists

Two words that differ by a single sound — the core of phonological therapy. Browse free word lists grouped by the process they target (velar fronting, gliding, voicing, and more).

How these developmental norms were built

The two ages for every sound come from McLeod & Crowe (2018), a scoping review of children's consonant acquisition across 27 languages, and its United States English companion, Crowe & McLeod (2020) — both published in the American Journal of Speech-Language Pathology (AJSLP). Rather than measuring one small group of children, these reviews pool data across many independent studies, which is why speech-language pathologists treat them as reference norms rather than any single lab's result.

Two honest limits are worth knowing. First, the ages describe children learning American English as their main language; bilingual children and speakers of dialects such as African American English follow their own, equally typical timelines. Second, the research covers single consonants and digraphs i A digraph is two letters that spell one sound — like sh, ch, or th. — not two-consonant blends — which is why the blend lists above carry practice words but no mastery age.

The word lists themselves — over 2,000 words sorted by position — come from Sound Safari's practice library, the same content the app uses in sessions. Everything here is informational, not diagnostic; only a qualified speech-language pathologist can evaluate a child directly.