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Descriptive results for the four sound categories: (a) vowels (alone), (b) approximants, (c) oral obstruents, and (d) glottal obstruents. The bars represent the mean percentage produced with a closed velopharynx throughout the utterance (dark portion of bars) and with a closed velopharynx during part of the utterance (light portion of bars) across age (in months). The numbers above the bars indicate the number of participants who produced usable vowel data at each age level.
