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Speech & Language Norms by Age

Developmental reference data for 11ages, 2 through 12 — MLU, NDW, TTR, PCC, intelligibility, Brown’s stage, language and speech milestones, red flags, and clinical guidance.

Sources: Rice et al. 2010 (MLU), Pavelko & Owens 2017 (SUGAR), Miller 1991 (SALT), Shriberg et al. 1997 (PCC), Hustad et al. 2021 (intelligibility), Brown 1973 (stages).

Age 2

Speech and Language Norms for Age 2

Two-year-olds average about 50-300 words, combine two-word phrases, and are about 50% intelligible to strangers.

MLU
1.9
PCC
50%
Intelligibility
50%

Brown's Stage I to early Stage II

View full norms Age 3

Speech and Language Norms for Age 3

Three-year-olds use three- to four-word utterances, master most early morphemes, and are roughly 75% intelligible to strangers.

MLU
3.1
PCC
70%
Intelligibility
75%

Brown's Stage II to Stage III

View full norms Age 4

Speech and Language Norms for Age 4

Four-year-olds average about 4.5 morphemes per utterance, tell simple stories, and are nearly 100% intelligible even to strangers.

MLU
4.4
PCC
85%
Intelligibility
95%

Brown's Stage IV to early Stage V

View full norms Age 5

Speech and Language Norms for Age 5

Five-year-olds produce well-formed complex sentences, understand most school vocabulary, and are fully intelligible — residual errors are limited to late-developing sounds.

MLU
5.0
PCC
92%
Intelligibility
100%

Brown's Stage V to post-V+

View full norms Age 6

Speech and Language Norms for Age 6

Six-year-olds use adult-like sentence structure, tell cohesive multi-episode stories, and should have no speech errors beyond /r/, late /s/ distortions, and occasional /th/.

MLU
5.5
PCC
95%
Intelligibility
100%

Post Brown's V+ (adult-like syntax)

View full norms Age 7

Speech and Language Norms for Age 7

Seven-year-olds read simple text independently, produce mature narrative structure, and should have no remaining speech errors except possibly residual /r/ or /s/ distortions.

MLU
6.0
PCC
96%
Intelligibility
100%

Adult-like syntax; Brown's framework no longer diagnostic

View full norms Age 8

Speech and Language Norms for Age 8

Eight-year-olds read to learn, tell cohesive expository narratives, and have fully mastered all speech sounds including /r/, /l/, and /s/ in most speakers.

MLU
6.4
PCC
98%
Intelligibility
100%

Adult-like syntax

View full norms Age 9

Speech and Language Norms for Age 9

Nine-year-olds understand multi-meaning words, use mature conjunctions and adverbials, and produce well-structured written paragraphs.

MLU
6.7
PCC
99%
Intelligibility
100%

Adult-like syntax

View full norms Age 10

Speech and Language Norms for Age 10

Ten-year-olds produce sophisticated oral and written narratives, understand figurative language, and use language to reason through multi-step problems.

MLU
7.0
PCC
99%
Intelligibility
100%

Adult-like syntax

View full norms Age 11

Speech and Language Norms for Age 11

Eleven-year-olds use adult-like vocabulary and syntax, produce well-organised written essays, and understand multi-step figurative and inferential language.

MLU
7.3
PCC
99%
Intelligibility
100%

Adult-like syntax

View full norms Age 12

Speech and Language Norms for Age 12

Twelve-year-olds use the full adult language system — complex reasoning, abstract vocabulary, and adult-like written expression — with only curriculum-specific vocabulary still to be acquired.

MLU
7.6
PCC
99%
Intelligibility
100%

Adult-like syntax

View full norms