Normal vowel articulations between 15 and 36 months of age

The results of a longitudinal study of normal vowel articulations are reported. Data were collected from four children at 15, 18, 21, 24 and 36 months of age. All phonetically transcribable vocalizations (glossable and non-glossable) were analysed to form an inventory of vowel types. Results of the analysis yielded a greater variety of vowel types compared to previous studies examining glossable utterances. The general pattern of development was less precise than the pattern previously reported for vowel accuracy studies. Lax and tense vowels occurred in equal numbers as did front and back vowels. The advantages and clinical value of considering non-glossable vocalizations in the assessment of young children's articulatory abilities are discussed.