<P> Infants produce cooing sounds when they are content . Cooing is often triggered by social interaction with caregivers and resembles the production of vowels . </P> <P> Infants produce a variety of vowel - and consonant - like sounds that they combine into increasingly longer sequences . The production of vowel sounds (already in the first 2 months) precedes the production of consonants, with the first back consonants (e.g., (g), (k)) being produced around 2--3 months, and front consonants (e.g., (m), (n), (p)) starting to appear around 6 months of age . As for pitch contours in early infant utterances, infants between 3 and 9 months of age produce primarily flat, falling and rising - falling contours . Rising pitch contours would require the infants to raise subglottal pressure during the vocalization or to increase vocal fold length or tension at the end of the vocalization, or both . At 3 to 9 months infants don't seem to be able to control these movements yet . </P> <P> Reduplicated babbling contains consonant - vowel (CV) syllables that are repeated in reduplicated series of the same consonant and vowel (e.g., (bababa)). At this stage, infants' productions resemble speech much more closely in timing and vocal behaviors than at earlier stages . Starting around 6 months babies also show an influence of the ambient language in their babbling, i.e., babies' babbling sounds different depending on which languages they hear . For example, French learning 9 - 10 month - olds have been found to produce a bigger proportion of prevoiced stops (which exist in French but not English) in their babbling than English learning infants of the same age . This phenomenon of babbling being influenced by the language being acquired has been called babbling drift . </P> <P> Infants now combine different vowels and consonants into syllable strings . At this stage, infants also produce various stress and intonation patterns . During this transitional period from babbling to the first word children also produce "protowords", i.e., invented words that are used consistently to express specific meanings, but that are not real words in the children's target language . Around 12--14 months of age children produce their first word . Infants close to one year of age are able to produce rising pitch contours in addition to flat, falling, and rising - falling pitch contours . </P>

When a young infant hears the same sound over and over such as ba-ba-ba- what will happen