Approximately 75 percent are of low intelligence while 10 percent may demonstrate high intelligence in specific areas such as math. The most intensive period of speech and language development is during the first three years of life, a period when the brain is developing and maturing. These skills appear to develop best in a world that is rich with sounds, sights, and consistent exposure to the speech and language of others. At the root of this development is the desire to communicate or interact with the world. The beginning signs of communication occur in the first few days of life when an infant learns that a cry will bring food, comfort, and companionship.
Newborns also begin to recognize important sounds such as the sound of their mother's voice.
Research has shown that by 6 months of age, most children recognize the basic sounds of their native language. Babbling soon turns into a type of nonsense speech called jargon that often has the tone and cadence of human speech but does not contain real words. By the end of their first year, most children have mastered the ability to say a few simple words. Children are most likely unaware of the meaning of their first words, but soon learn the power of those words as others respond to them. During this period children rapidly learn that words symbolize or represent objects, actions, and thoughts.