Intrinsic F0 of vowels in the babbling of 6-, 9-, and 12-month-old French- and English-learning infants.

In every language so far examined, high vowels such as [i] and [u] tend to have higher fundamental frequencies (F0s) than low vowels such as [a]. This intrinsic F0 effect (IF0) has been found in the speech of children at various stages of development, except in the one previous study of babbling. The present study is based on a larger set of utterances from more subjects (six French- and six English-learning infants), at the ages 6, 9, and 12 months. It is found, instead, that IF0 appears even in babbling. There is no indication in these data of a developmental trend for the effect, and no indication of a difference due to the target language. These results support the claim that IF0 is an automatic consequence of producing vowels.