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This work investigates laryngeal and supralaryngeal correlates of the voicing contrast in alveolar obstruent production in German. It further studies laryngealoral co-ordination observed for such productions. Three different positions of the obstruents are taken into account: the stressed, syllable initial position, the post-stressed intervocalic position, and the post-stressed word final position. For the latter the phonological rule of final devoicing applies in German. The different positions are chosen in order to study the following hypotheses:
1. The presence/absence of glottal opening is not a consistent correlate of the voicing contrast in German.
2. Supralaryngeal correlates are also involved in the contrast.
3. Supralaryngeal correlates can compensate for the lack of distinction in laryngeal adjustment.
Including the word final position is motivated by the question whether neutralization in word final position would be complete or whether some articulatory residue of the contrast can be found.
Two experiments are carried out. The first experiment investigates glottal abduction in co-ordination with tongue-palate contact patterns by means of simultaneous recordings of transillumination, fiberoptic films and Electropalatography (EPG). The second experiment focuses on supralaryngeal correlates of alveolar stops studied by means of Electromagnetic Articulography (EMA) simultaneously with EPG. Three German native speakers participated in both recordings. Results of this study provide evidence that the first hypothesis holds true for alveolar stops when different positions are taken into account. In fricative production it is also confirmed since voiceless and voiced fricatives are most of the time realised with glottal abduction. Additionally, supralaryngeal correlates are involved in the voicing contrast under two perspectives. First, laryngeal and supralaryngeal movements are well synchronised in voiceless obstruent production, particularly in the stressed position. Second, supralaryngeal correlates occur especially in the post-stressed intervocalic position. Results are discussed with respect to the phonetics-phonology interface, to the role of timing and its possible control, to the interarticulatory co-ordination, and to stress as 'localised hyperarticulation'.
Articulatory token-to-token variability not only depends on linguistic aspects like the phoneme inventory of a given language but also on speaker specific morphological and motor constraints. As has been noted previously (Perkell (1997), Mooshammer et al. (2004)), speakers with coronally high "domeshaped" palates exhibit more articulatory variability than speakers with coronally low "flat" palates. One explanation for that is based on perception oriented control by the speaker. The influence of articulatory variation on the cross sectional area and consequently on the acoustics should be greater for flat palates than for domeshaped ones. This should force speakers with flat palates to place their tongue very precisely whereas speakers with domeshaped palates might tolerate a greater variability. A second explanation could be a greater amount of lateral linguo-palatal contact for flat palates holding the tongue in position. In this study both hypotheses were tested.
In order to investigate the influence of the palate shape on the variability of the acoustic output a modelling study was carried out. Parallely, an EPG experiment was conducted in order to investigate the relationship between palate shape, articulatory variability and linguo-palatal contact.
Results from the modelling study suggest that the acoustic variability resulting from a certain amount of articulatory variability is higher for flat palates than for domeshaped ones. Results from the EPG experiment with 20 speakers show that (1.) speakers with a flat palate exhibit a very low articulatory variability whereas speakers with a domeshaped palate vary, (2.) there is less articulatory variability if there is lots of linguo-palatal contact and (3.) there is no relationship between the amount of lateral linguo-palatal contact and palate shape. The results suggest that there is a relationship between token-to-token variability and palate shape, however, it is not that the two parameters correlate, but that speakers with a flat palate always have a low variability because of constraints of the variability range of the acoustic output whereas speakers with a domeshaped palate may choose the degree of variability. Since linguo-palatal contact and variability correlate it is assumed that linguo-palatal contact is a means for reducing the articulatory variability.
Articulatory token-to-token variability not only depends on linguistic aspects like the phoneme inventory of a given language but also on speaker specific morphological and motor constraints. As has been noted previously (Perkell (1997), Mooshammer et al. (2004)) , speakers with coronally high "domeshaped" palates exhibit more articulatory variability than speakers with coronally low "flat" palates. One explanation for that is based on perception oriented control by the speaker. The influence of articulatory variation on the cross sectional area and consequently on the acoustics should be greater for flat palates than for domeshaped ones. This should force speakers with flat palates to place their tongue very precisely whereas speakers with domeshaped palates might tolerate a greater variability. A second explanation could be a greater amount of lateral linguo-palatal contact for flat palates holding the tongue in position. In this study both hypotheses were tested.
Studying kinematic behavior in speech production is an indispensable and fruitful methodology in order to describe for instance phonemic contrasts, allophonic variations, prosodic effects in articulatory movements. More intriguingly, it is also interpreted with respect to its underlying control mechanisms. Several interpretations have been borrowed from motor control studies of arm, eye, and limb movements. They do either explain kinematics with respect to a fine tuned control by the Central Nervous System (CNS) or they take into account a combination of influences arising from motor control strategies at the CNS level and from the complex physical properties of the peripheral speech apparatus. We assume that the latter is more realistic and ecological. The aims of this article are: first, to show, via a literature review related to the so called '1/3 power law' in human arm motor control, that this debate is of first importance in human motor control research in general. Second, to study a number of speech specific examples offering a fruitful framework to address this issue. However, it is also suggested that speech motor control differs from general motor control principles in the sense that it uses specific physical properties such as vocal tract limitations, aerodynamics and biomechanics in order to produce the relevant sounds. Third, experimental and modelling results are described supporting the idea that the three properties are crucial in shaping speech kinematics for selected speech phenomena. Hence, caution should be taken when interpreting kinematic results based on experimental data alone.