The acoustics of word stress in English as a function of stress level and speaking style

This study of lexical stress in English is part of a series of studies, the goal of which is to describe the acoustics of lexical stress for a number of typologically different languages. When fully developed the methodology should be applicable to any language. The database of recordings so far includes Brazilian Portuguese, English (U.K.), Estonian, German, French, Italian and Swedish. The acoustic parameters examined are f0-level, f0-variation, Duration, and Spectral Emphasis. Values for these parameters, computed for all vowels, are the data upon which the analyses are based. All parameters are tested with respect to their correlation with stress level (primary, secondary, unstressed) and speaking style (wordlist reading, phrase reading, spontaneous speech). For the English data, the most robust results concerning stress level are found for Duration and Spectral Emphasis. f0-level is also significantly correlated but not quite to the same degree. The acoustic effect of phonological secondary stress was significantly different from primary stress only for Duration. In the statistical tests, speaker sex turned out as significant in most cases. Detailed examination showed, however, that the difference was mainly in the degree to which a given parameter was used, not how it was used to signal lexical stress contrasts. The research programme has been funded by the Swedish Research Council (VR) project A typology for word stress and speech rhythm based on acoustic and perceptual considerations, under grant 2007-2301.