Makes cooing sounds (aah, ooh)
What is this milestone?
First vocal sounds beyond crying
Cooing consists of soft, musical vowel sounds like 'aah,' 'ooh,' and 'eee.' These are the first non-crying vocalizations your baby will make as they begin to explore the physical mechanics of using their voice.
Why it matters
Cooing is the earliest form of expressive language. By experimenting with these open, airy sounds, your baby is strengthening the muscles in their mouth, throat, and vocal cords, preparing them for more complex speech down the line.
What to expect leading up to it
You'll often hear these sounds when your baby is relaxed, happy, or looking at a stimulating toy. They might start as accidental sighs that gradually become more frequent and intentional as they realize they have a voice.
How to encourage and support it
Have 'cooing conversations' by imitating their sounds and pausing for them to 'reply.' Narrate your day, sing songs, and give them plenty of face-to-face time. Your enthusiastic responses teach them the powerful mechanics of dialogue.
When to talk to your doctor
The CDC's milestone checklists say what most children (75% or more) can do by each age. They list “Makes sounds like ‘oooo’, ‘aahh’ (cooing)” by 4 months. If your child is not doing this by then, the CDC's advice is not to wait: talk with your child's doctor, share your concerns, and ask about developmental screening. The same goes at any age if your child loses a skill they once had, or if anything else about their development worries you. Source: the CDC's “Learn the Signs. Act Early.” milestone checklists, checked October 5, 2026.
Every child develops at their own pace, and the ages here are the CDC's general guidance — not a developmental screening. This article is not medical advice and is not a substitute for your pediatrician. If you have any concern about your child's development, talk to them.
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