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# Language development and speech red flags

- Concept

Children understand before they speak: cooing, babbling, first words near 1 year and sentences by 3. Any delay needs a hearing test.

Updated Nov 5, 2026

## Key points

- Receptive language comes before expressive: a 1-year-old understands far more words than he or she says.
- Sequence: cooing (about 2 to 4 months), babbling (about 6 to 9 months), first words (about 12 months), two-word phrases (about 2 years), sentences (3 to 4 years).
- Hearing loss is the first cause to rule out in any speech or language delay.
- Learning two languages does not cause language delay.
- Loss of words or babbling at any age is a red flag.
- Speech disorders (articulation, stuttering) are different from language disorders (understanding and forming sentences).

## What it is

Language is the system of words and rules used to understand (receptive) and express (expressive) meaning; speech is the motor act of producing sounds. Language develops in a fixed order across cultures, from cooing to babbling, first words, word combinations and sentences, with understanding always ahead of speaking. Hearing is the foundation, so any delay starts with a hearing test.

## Key facts

- Joint attention (looking at the same thing as another person and pointing to share it) is a foundation of language and is reduced in autism.
- Developmental disfluency (repeating whole words or phrases) is common between about 2 and 5 years; part-word repetitions, blocks, tension or distress suggest stuttering that needs assessment.
- In bilingual children, the vocabulary of both languages together is what counts.
- Talking, reading and playing with the child supports language; differences in how much speech children hear are linked to later school achievement.

## Language milestones and warning signs

| Age | Typical skills | Reason to evaluate |
| --- | --- | --- |
| 0 to 3 months | Reacts to loud sounds; coos; different cries for different needs | No reaction to loud sounds |
| 4 to 9 months | Follows sounds with the eyes; laughs; babbles (ba, ma); turn-taking sounds | No babbling or vocal play by 9 months |
| 9 to 12 months | Understands no and common words; waves; first words with meaning | No gestures (pointing, waving) by 12 months |
| 12 to 24 months | Points to body parts; follows simple commands; new words every week; two-word phrases by 2 years | No words by about 15 to 16 months; no two-word phrases by 2 years |
| 2 to 3 years | About 50 words by 30 months; phrases of two or three words; understood by family | Speech hard for family to understand at 3 years |
| 3 to 5 years | Who, what, where, why questions; sentences of four or more words; stories; rhymes | No sentences, or speech unclear to strangers, at 4 years |

## Clinical notes

- First steps in a delay: a formal hearing test (audiology), a check of social communication for autism, and a look at other domains for global delay.
- Recurrent ear infections with fluid in the middle ear can cause fluctuating hearing loss and slow speech.
- Referral to a speech and language professional and early intervention should not wait for a ‘late talker’ to catch up on his or her own.

## Memory aid

Coo, babble, word, pair, sentence: understanding always walks one step ahead of speech, and hearing leads the way.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the first test in any child with speech or language delay?

A formal hearing test, because hearing loss is a common and treatable cause.

## Does growing up with two languages cause language delay?

No. Bilingual children reach milestones on time when both languages are counted together.

## What is the difference between a speech disorder and a language disorder?

Speech is producing sounds (articulation, fluency); language is understanding and using words and grammar.

## Which language finding by 2 years calls for evaluation?

No two-word phrases, or poor understanding of simple directions, at 2 years.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/behavioral-science/language-development-and-speech-red-flags/)

## Elsewhere in DurgiPedia

- [The cerebral cortex and language](https://durgical.com/en/physiology/the-cerebral-cortex-and-language/)
- [Hearing: middle ear, cochlea and auditory pathway](https://durgical.com/en/physiology/hearing-middle-ear-cochlea-and-auditory-pathway/)

## Connections

## Related 5

- [Developmental milestones: domains, corrected age and red flags](https://durgical.com/en/behavioral-science/developmental-milestones-domains-corrected-age-and-red-flags/)
- [Milestones of the first year](https://durgical.com/en/behavioral-science/milestones-of-the-first-year/)
- [Milestones from 1 to 3 years](https://durgical.com/en/behavioral-science/milestones-from-1-to-3-years/)
- [Milestones from 4 years to school age](https://durgical.com/en/behavioral-science/milestones-from-4-years-to-school-age/)
- [Piaget's stages of cognitive development](https://durgical.com/en/behavioral-science/piaget-s-stages-of-cognitive-development/)

## Related conditions 5

- [Autism spectrum disorder (ASD)](https://durgical.com/en/conditions/autism-spectrum-disorder/)
- [Hearing loss (conductive and sensorineural, including sudden hearing loss)](https://durgical.com/en/conditions/hearing-loss/)
- [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/)
- [Fragile X syndrome](https://durgical.com/en/conditions/fragile-x-syndrome/)
- [Otitis media with effusion and chronic suppurative otitis media](https://durgical.com/en/conditions/otitis-media-with-effusion-and-chronic-suppurative-otitis-media/)

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Educational content on behavior and the clinical relationship; not a diagnostic or treatment guide and no substitute for assessment by a health professional. If you or someone near you is at risk, seek help now from an emergency service or a mental-health helpline.

Sources: [Speech and Language Developmental Milestones](https://www.nidcd.nih.gov/health/speech-and-language) (National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 2022); [Milestones by 2 Years](https://www.cdc.gov/act-early/milestones/2-years.html) (Centers for Disease Control and Prevention (CDC), 2026); [Milestones by 3 Years | Learn the Signs. Act Early. | CDC](https://www.cdc.gov/act-early/milestones/3-years.html) (Centers for Disease Control and Prevention (CDC), 2026).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/behavioral-science/language-development-and-speech-red-flags/