In this paper, a deductive approach to the study of vocal tract characteristics, vowel, vowel-to-vowel and vowel-consonant-vowel productions is presented. The distinctive region model, deduced from acoustic theory, is used to develop this approach. The model is characterized by simplicity and efficiency in its handling of the articulatory-acoustic relation. Vowel systems can be explained by means of this approach. A tentative study on the predictability of vowel-to-vowel characteristics is also presented. The obtained results suggest that the human communication system is driven by physical laws of the real world.