Stress Distinction in German: Modeling Kinematic Parameters of Tongue Tip Gestures

Unstressed syllables are produced by a reduction of movement amplitudes and durations compared to stressed syllables. In order to investigate the effect of deaccentuation on tongue tip gestures in /tVt/ sequences with all vowels of German we recorded tongue tip movements of five speakers by means of EMMA. The movement paths of stressed items were manipulated to simulate kinematic parameters of unstressed items in three different ways: truncation, rescaling and combined truncation and rescaling. The following parameter of simulated movements were compared to measured unstressed items: durations and peak velocities of opening and closing movements, overall distance during syllable, the interval between velocity peaks in percent of syllable duration and the number of acceleration peaks between velocity peaks. The results indicate that no type of simulation can account for all parameters in all vocalic contexts. The combined simulation resembled most closely the kinematic parameters of unstressed items but could not generate the smaller amplitudes of lax unstressed syllables, 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.