By this age the child will coo and make noises in response to speech.
Birth to Five Months!
At this age, the child will ask and answer why questions, engage in conversation and use sentences with 8 words or more.
5 years old!
At this age, a child's speech is 90-100% intelligible though some speech errors may persist. Receptively, a child is able to group and categorize items and understand complex questions.
4 years old!
By this age, a child will begin to combine two words and will have a vocabulary of at least 50 words.
18 - 23 months!
By this age a child will use 3-word sentences, ask simple questions with inflection and speech intelligibility is approximately 50-75%.
2-3 years old!