In what stage of phonological development do pre-linguistic children start to coo?

• A. Stage 3 (3 - 8 months)
• B. Stage 1 (0 - 2 months)
• C. Stage 4 (5 - 10 months)
• D. Stage 2 (1 - 4 months)

Answer: (D)

Coos are early vowel-like vocalizations that signal a move from purely reflexive sounds to more purposeful vocal output. In this stage, infants begin to produce sustained, lighter, vowel-dominant sounds (often in response to social interaction) with relaxed vocal tract control. This period falls around one to four months, so cooing is typically part of Stage 2. It’s distinct from the very first weeks, which are dominated by reflexive crying and vegetative noises, and from later stages that introduce consonant-like babbling and more complex sound play. Coos show the infant beginning to use the vocal apparatus in a more controlled way, laying the groundwork for later speech development.