Infants follow a general timeline of vocal developments in childhood.[13] This timeline provides a general outline of expected developments from birth to age one. Babbling usually lasts 6–9 months in total.[4] The babbling period ends at around 12 months because it is the age when first words usually occur. However, individual children can show large variability and this timeline is only a guideline.
From birth to 1 month, babies produce mainly pleasure sounds, cries for assistance, and responses to the human voice.[13]
Around 2 months, babies can distinguish between different speech sounds, and can make “goo”ing sounds [13]
Around 3 months, babies begin (making elongated vowel sounds "oooo" "aaaa"), and will respond vocally to speech of others. They continue to make predominantly vowel sounds.[13]
Around 4 months, babies may vary their pitch, and imitate tones in adult speech.[13]
Around 5 months, babies continue to experiment with sound, imitating some sounds made by adults.[13]
Around 6 months, babies vary volume, pitch and rate. When infants are 6 months old they are finally able to control the opening and closing of the vocal tract, and upon obtaining this ability, infants begin to distinguish between the different sounds of vowels and consonants. This age is often distinguished as the beginning of the canonical stage. During the canonical stage, the babbling involves reduplicated sounds containing alternations of vowels and consonants, for example, "baba" or "bobo".[13] Reduplicated babbling (also known as canonical babbling) consists of repeated syllables consisting of consonant and a vowel such as "da da da da" or "ma ma ma ma".[14]
Around 7 months, babies can produce several sounds in one breath, and they also recognize different tones and inflections in other speakers.[13]
Around 8 months, babies can repeat emphasized syllables.[13] They imitate gestures and tonal quality of adult speech. They also produce variegated babbling. Variegated babbles contain mixes of consonant vowel combinations such as "ka da by ba mi doy doy".[15] Variegated babbling differs from reduplicated babbling in terms of the variation and complexity of syllables that are produced.[6]
Around 9–10 months, babies can imitate non speech sounds, and speech-like sounds if they are in the child's repertoire of sounds.[13] Infant babbling begins to resemble the native language of a child. The final stage is known as conversational babbling, or the "jargon stage". Usually occurring by about ten months of age, the jargon stage is defined as "pre-linguistic vocalizations in which infants use adult-like stress and intonation".[16] The general structure of the syllables that they are producing is very closely related to the sounds of their native language and this form of babbling significantly predicts the form of early words.[17]
Around 11 months, babies imitate inflections, rhythms, and expressions of speakers.[13]
By 12 months, babies typically can speak one or more words. These words now refer to the entity which they name; they are used to gain attention or for a specific purpose.[13] Children continue to produce jargon babbles beyond their first words.