In the first year of life infants do not yet produce vowels in a full sense of the word. Yet, for the tuned-in listener the infant's sound can elicit a vowel-like perception that, with age, becomes more adult-like. Mastering the vowels from the ambient language also means dealing with developmental changes in the speech mechanism and in perception. An enormous variability in vocalic productions is found. The Principal Component Analysis method on band filter data employed in this study focuses on the spectral envelope, and thus accounts for frequency as well as intensity information, much like the information used by the ear. Results for Russian-learning infants indicate that between 6 months and two years of age the infants explore the vowel space in quite different manners. Data on 5 Dutch boys, acquiring 12 vowels, are compared to the Russian results, to interpret the influence of the number of vowels per language.
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