Stress distinction in German: simulating kinematic parameters of tongue-tip gestures.

Abstract

Levels of stress are not only distinguished by varying fundamental frequency contours but also by changes of supralaryngeal parameters, e.g., unstressed syllables exhibit reduced movement amplitudes and durations compared with stressed syllables. To investigate the effect of deaccentuation on apical gestures in /tVt/ sequences with all vowels of German, we recorded lingual movements of five speakers by means of EMMA. Movement paths of recorded stressed items were manipulated to simulate kinematic parameters of recorded unstressed items in three different ways: truncation, rescaling and combined truncation and rescaling. We assumed that the simulation type that generated parameters most similar to recorded unstressed items can be interpreted in terms of a generalized motor program for deaccentuation. The following parameters of simulated movements were compared with measured unstressed items: movement durations, peak velocities, distances, interval between velocity peaks in percent of syllable duration, symmetry of velocity profiles and number of acceleration peaks between velocity peaks. Combined simulations resembled most closely the kinematic parameters of unstressed items but could not generate the smaller amplitudes of unstressed syllables with lax vowels, since durational reduction of lax vowels due to deaccentuation was very small, i.e., the spatial reduction was not proportional to the temporal reduction for lax items. Therefore, it can be concluded that with the method used here no single parameter or pattern could be found whose manipulation results in the kinematic characteristics of unstressed syllables, which speaks against the concept of a generalized motor program for deaccentuation.