The nature of vowel structures.

Abstract

The Dispersion-Focalization Theory (DFT) attempts to predict vowel systems by using the competition between two perceptual costs: (i) dispersion based on inter-vowel distances, (ii) local focalization based on intra-vowel spectral salience related to formants proximity. The first cost is related to the global structure of the system and the second to the internal structure of each vowel element. The competition takes place in an auditory (formant-based) space, and it is controlled by two parameters, namely λ which sets the respective weight of F1 and higher formants in auditory distances, and α which sets the respective weights of the dispersion and focalization costs. We describe a new methodology for testing the DFT predictions: for a given number of vowels, the so-called “phase spaces” allow us to determine the DFT winner in the (λ, α) space. We present a refined analysis of the UPSID database inventory of vowel systems. From the comparison between experimental phase spaces and UPSID data we not only derive a (λ, α) region for which DFT predictions fit quite well with the phonological inventories and are compatible with preferred 3-to-7 vowels systems, but also what the possible variants in the systems are and in which order they can appear.