A baby's first sounds are met with joyous celebration by parents. Initial cooing progresses to babbling and then to baby's first words, usually "mama" or "dada."

The first 24 months are a critical period for speech and language development. This means that the growing brain is best able to absorb language during this time.

It's important to remember that children vary greatly in their speech and language development. Speech and language milestones serve as a general guide to normal development. They also help doctors and other health professionals determine when a child may need extra help to learn to speak or use language.

Milestones at the end of 3 months

• Begins to babble
• Laughs
• Begins to imitate sounds
• Turns head toward direction of sound

Milestones at the end of 7 months

• Responds to own name
• Begins to respond to "no"
• Responds to sound by making sounds
• Babbles chains of consonants (usually sounds for m, b, d)
• Uses voice to express pleasure and displeasure

Milestones at the end of 12 months

• Responds to simple verbal requests
• Responds to "no"
• Babbles with inflection
• Says "dada" and "mama," which correlates with the person
• Uses exclamations, such as "oh-oh!"
• Tries to imitate words

Milestones at the end of 18 months

• Points to object or picture when it's named
• Recognizes names of familiar people, objects and body parts
• Says 4-6 single words (by 15 to 18 months)

Milestones at the end of 24 months

• Knows and says about 50 words with two to three syllables
• Uses simple phrases
• Speech understandable about 50 percent of the time
• Begins using simple prepositions, such as "with" and "for"

Talk to your child's doctor if you have concerns about your child's speech development. Speech delays occur for many reasons. Causes include:

• Hearing loss
• Delayed development
• Mental retardation
• Autism
• Elective mutism (the child chooses not to talk)
• Cerebral palsy

Your doctor may refer you to a speech and language specialist. This person will test your child's speech. He or she may use a game-like test with earphones to check for hearing loss or deafness. In some cases, a complete physical and neurologic exam may be recommended.