Relation between acoustic-phonetic properties and speech intelligibility in noise obtained with bilingual talkers

Abstract

An objective, language-independent way of predicting observed differences in speech intelligibility in noise across talkers based on their acoustic-phonetic properties was pursued by exploiting speech intelligibility data in stationary speech-shaped noise uttered by bilingual talkers and comparing inter-individual as well as intra-individual speech feature variations across languages. Matrix sentence materials were used that were uttered by bilingual talkers of German/Spanish and of German/Russian and by the respective original matrix test talkers. Various acoustic-phonetic parameters discussed in the literature as being related to speech intelligibility were determined for each talker. Vowel space area, between-vowel category dispersion, and energy in the mid-frequency region represented by the speech intelligibility index were found to be language-independent acoustic-phonetic properties most strongly related to speech intelligibility at least for German, Russian and Spanish. Generally larger inter-individual variation within languages than intra-individual variation across languages was found. Hence, objective phonetic criteria like vowel space area may be used in the future to objectively assess the potential of a talker to be easily understood in a noisy background. One reason of the generally poorer intelligibility performance of Spanish compared to German or Russian may lie in the usage of considerably smaller vowel space areas.