Acoustic characteristics of lexical stress in continuous speech

We investigate acoustic differences between vowels in syllables that do or don´t carry lexical stress. The speech material on which the investigation is based differs from the type of material used in previous research: we used phonetically rich sentences from the Dutch POLYPHONE corpus. We discuss the definition of the linguistic feature `lexical stress´ and its possible impact on the phonetic realization. We then proceed to explain the experiments that were carried out and the presentation of the results. Although most of the duration, energy and spectral tilt features that we used in the investigation show statistically significant differences for the population means for stressed and unstressed vowels, it also appears that the distributions overlap to such an extent that automatic detection of stressed and unstressed syllables yields accuracy scores of not much more than 65%. It is argued that this is due to the large variety in the ways in which the abstract linguistic feature `lexical stress´ is realized in the acoustic speech signal