The perception of lexical stress in Spanish

As in other languages, stress in Spanish is signaled by three simultaneous acoustic cues: fundamental frequency (F0), duration and intensity. In this experiment, the role of these parameters in the perception of lexical stress in isolated words has been studied using natural resynthesized speech. Results show that the F0 contour alone is not enough to allow the identification of the stressed syllable of a word. However, in combination with duration, intensity or both duration and intensity, F0 is a relevant acoustic cue for the perception of lexical stress. On the other hand, intensity and duration, either combined or in isolation, are not sufficient for the identification of the stressed syllable within a word. It is generally acknowledged that, as in other languages, stress in Spanish is signaled by three simultaneous acoustic cues: fundamental frequency (F0), duration and intensity. An earlier perceptual study using synthetic stimuli [1] concluded that, in Spanish, F0 is the only parameter systematically related to the identification of the stressed syllable of a word, while the role of duration depends on the stress pattern. The experiments with natural resynthesized speech reported in [2, 3] indicated that a replacement of the F0 contour is not enough to induce the identification of the stressed syllable if the other two parameters are not modified. Taking advantage of the fact that Spanish is a free accent language –i.e. lexical stress can appear in any syllable of the word– a perceptual experiment with natural resynthesized speech has been designed to assess the role of F0, duration and intensity in the identification of the stressed syllable in isolated words, using lexical items with the same segmental content but with differences in stress placement. To take into account the role of lexical knowledge, phonologically acceptable but non-existent words have also been included in the test corpus. The contribution of each acoustic cue has been examined both in isolation and in combination with other cues. 2. EXPERIMENTAL PROCEDURE The primary data for the experiment has been extracted from the analysis of a corpus of isolated words read by a native speaker of Castilian Spanish. The recordings have then been manipulated to obtain the test stimuli following the procedure explained below. The recorded corpus consisted of four meaningful three syllable words with constant CV structure allowing the stress to be placed on the first (proparoxytone), second (paroxytone) and final (oxytone) syllable –numero, numero, numero; limite, limite, limite; medico, medico, medico; valido, valido, valido– and four meaningless words in which the position of the stress has also been varied –*nulibo, *nulibo, *nulibo; *ladebo, *ladebo, *ladebo; *maledo, *maledo, *maledo; *luguido, *luguido, *luguido–. The 240 target words (10 repetitions of 8 words x 3 stress patterns) were analyzed using the Praat