Hi, I need to ask I have a son turning 3 in May 2011. He does not respond to sound but when he was much youger he can actually respond to sound and can call out some simple words. But for now he can only say out mama, papa and some other words but not responding to me calling him or to sounds.

Had sent him to Speech Therapy and to Hearing Test.

Is it true some kids is very slow development and can take till 4-5years to talk.

Being that you have had the hearting test and speech testing done, I would say the next step is a psychologist. Autism (and many other issues such as global delays and others, but I am most familiar with Autism) likes to come around at 3 years old, and it greatly affects speech, and hearing, though the child will HEAR the sounds and words, it may not REGISTER.

Either way, a doctor appointment, and psychiatrist appointment, definitely would benefit here.