At the earliest stage, infants recognize their mother's voice and turn toward familiar voices when they are spoken to. Some infants will smile and make sounds that indicate pleasure. They start to express themselves by crying differently for different needs and use sounds such as cooing to respond to human voices.
Between the ages of 3 and 6 months, infants turn toward the speaker and are fascinated with movements of the mouth when a person is talking. At this stage of language development, infants start to mimic sounds and add consonants like "p," "b" and "m" to the vowel-like cooing sounds of earlier months. They can now respond to the tone of a speaker's voice and begin to babble to get attention. The sounds an infant makes at this stage are universal throughout the world, indicating that people are born with the ability to learn any language.
This age brings a vital stage of language development. Children can now recognize words such as "dada," "mama" and "bye-bye." They now babble with up to 12 different sounds, repeat syllables and express their mood with sound. By the time they are 9 months old, babies start to recognize words for common objects and the names of familiar people. They can understand the word "no," and they know their names. Babies now voice most consonant and vowel sounds.
Between the ages of 12 and 15 months, toddlers begin to follow directions, use a few words and say the word "no." By the time they reach 18 months, they can usually understand simple words like "up" and "hot." Their vocabulary is increasing, and they can form sentences of two words. By the age of 3 years, toddlers engage in reading readiness activities such as listening and talking about daily activities. At this point, they start to develop an interest in reading, and learn that English text is read from left to right and top to bottom. By reading to their children, parents can help them learn grammar and the elements of a story.
Between 3 and 4 years old, children increase their vocabulary and use words for conversation. Some begin to develop a reading sight vocabulary and notice familiar words. As parents read books to their child, the child begins to make the connection between the spoken word and the words written on the page.