When it comes to speech, parents play an important part.
- Do you speak to your child with your child observing your lip movements?
- Do you encourage your child to speak (example insisting on hearing 'Please' before giving something, teach your child how to request 'Can I have ___?')?
- Do you expose your child to adequate vocabulary and opportunities to speak up?
- Do you set an example by talking to your child in proper english (no baby talk)?
The right environment also determines if the child can pick up language early.
My son was speaking like a bullet train at 18mths. Many vocab but talk too fast and end up inaudible. Reason being my family tend to talk very fast. But we exposed him to a wide vocab from young, speak to him in proper english/mandarin, allow him to observe our lip movements when we talk to him, encourage him to speak up (by forcing words of out him before giving him anything).
It takes patience. Try encouraging your child to talk more before you simply label him. If you did not provide the environment and opportunity, it's not the child's fault
If your child really refuses to speak or can't seem to be picking up new words or not making progress after you tried different ways to encourage your child, then seek professional help.