Between 8 and 12 months, the coos, gurgles, and other “baby” sounds become more like the sounds of the home language. In English, babies start to make recognizable syllables, like “ba,” “da,” “ga,” and “ma.” Babies may also stumble on words like “mama” and “bye-bye” accidentally, learning more about what they mean when they see the reaction from their caregivers. Although babies vary by several months when they begin speaking recognizable words, their speech at 12 months generally consists of gibberish that sounds like speech, with familiar tones and inflections. When babies experiment with sounds that vary in intensity, pitch, and quality, they are getting ready to talk.
Shelov, S. P. (Editor-in-Chief). (2004). Caring for Your Baby and Young Child: Birth to Age 5. The American Association of Pediatrics. Revised edition. New York: Bantam Books.