Objectivization of Phonological Evaluation of Speech Elements by Means of Audio Parametrization

Abstract

This study addresses two issues related to both machine- and subjective-based speech evaluation by investigating five phonological phenomena related to allophone production. Its aim is to use objective parametrization and phonological classification of the recorded allophones. These allophones were selected as specifically difficult for Polish speakers of English: aspiration, final obstruent devoicing, dark lateral /l/, velar nasal and pre-fortis clipping. A set of audio features based on mechanism of each phonological process was created. Recordings of phonetic material prepared by phonology expert were executed. First, several speakers were recorded while reading words from a teleprompter. Then, every word was played back from the previously recorded sample read by a phonology expert and each examined speaker repeated a particular word trying to imitate correct pronunciation. The next step consisted in partitioning by editing two recorded sets of words into allophones, then signals were analyzed and subsequently audio excerpts were parametrized. The comparison of two sets of allophones was reinforced by the phonology expert's assessment of produced speech sounds. Analyses presented in this paper allowed for discovering a set of parameters, which enable to determine whether the target processes were pronounced correctly.