Babbling (also called twaddling) is a stage in child language acquisition, during which an infant appears to be experimenting with uttering sounds of language, but not yet producing any recognizable words. (Crucially, the larynx or voicebox, originally high in the throat to let the baby breathe while swallowing, descends during 'the first year of life', allowing a pharynx to develop and all the sounds of human speech to be formed ). Babbling begins at approximately 5 to 7 months of age, when a baby's noises begin to sound like phonemes. Infants begin to produce recognizable words usually around 12 months, though babbling may continue for some time afterward.
Sarah Blaffer Hrdy writes, "...marmoset and tamarin babies also babble. It may be that the infants of cooperative breeders are specially equipped to communicate with caretakers. This is not to say that babbling is not an important part of learning to talk, only to question which came first—babbling so as to develop into a talker, or a predisposition to evolve into a talker because among cooperative breeders, babies that babble are better tended and more likely to survive."
Steven Pinker compares a child babbling to a person fiddling with a complex hi-fi system in an attempt to understand what the controls do. Most babbling consists of a small number of sounds, which suggests the child is preparing the basic sounds necessary to speak the language to which it is exposed.
Infants who are deaf also show vocal babbling, suggesting that early babbling arises from inherent human tendencies to use the vocable articulators in particular ways during early language acquisition. If they are exposed to sign language, they will babble with their hands at approximately the same time vocal babbling appears, although sign production appears a few months before word production generally does in hearing children.
At 0-4 months babies gurgle, and coo (vowel sounds such as "oooh" and "aah"). And at 4-6 months babies may start to babble (adding consonants: "gaga," "dada"). At 6-12 months of age, babies typically babble and enjoy vocal play as they experiment with a range of sounds. At 12-18 months, toddlers begin to use sound in a meaningful way. They utter one-syllable words, make sounds imitating cars and planes, and say things like, "uh oh." Toddlers also understand the meaning of some words they cannot yet say. They may also use one word to represent a whole sentence. For example, "Juice" may mean, "Mother, I would like some juice," "You are drinking juice," or "Oh look, there is juice in the cup." At age 18-24 months, toddlers repeat words and can link words into short sentences. They use approximately 50 words, but can understand many more. They may use short sentences, such as, "She go bye bye." And "What you doing?" They may also use familiar words incorrectly, e.g., a child with a pet dog might describe all large furry animals as "doggie."
According to Menn and Stoel Gammon in The Development of Language, “This early period of prelinguistic vocalization can be divided into five stages,” the first of which begins at about age six months. Stage one is crying, stage two is cooing, stage three is vocal play, and stage four is canonical babbling. The fifth and final stage is conversational babbling, also known as the "jargon stage (usually occurring by about ten months of age). This jargon stage is defined as: “Pre-linguistic vocalizations in which infants use adult like stress and intonation.”
Hence, babbling occurs during the first year of life if the child is developing normally. As the baby grows and changes, his/her vocalizations change as well. Babies use these vocalizations to communicate. They commence vocal development by crying, progress to loud yelling noises, and finally make speech.
Children who can't babble for some physiological reason, such as having a breathing tube in their throat, do subsequently acquire normal pronunciation but their speech development is significantly delayed.