0-3 months
Reacts to loud sounds with startle reflex; soothed by soft sounds; turns head to voice; smiles in response to voice
3-6 months
Looks/turns to new sound; responds to changes in voice; enjoys toys that make sounds; scared by loud voice
6-10 months
Responds to certain sounds even when not loud; babbles even when alone; recognizes some words, responds to directions
10-15 months
Plays with voice; points to familiar things when asked; imitates simple words and sounds
15-18 months
Points to some body parts when asked; knows 10-20 words; uses short sentences
18-24 months
Understands yes-no questions, simple phrases; points to pictures when asked
24-36 months
Understands certain phrases; follows two-step commands; understands action words
Child Studies and Development 