The Effect of Articulatory Constraints and Auditory Information on Patterns of Intrusions and Reductions

This dissertation seeks to answer the question whether articulatory constraints and auditory information affect intrusion and reduction errors. These intrusions and reductions of articulatory movement result from a general tendency to stabilize movement coordination. Stabilisation of speech movement coordination is an autonomous self-organizing process. This process, however, can be affected by factors related to articulatory properties and auditory information. To assess how these factors affect movement coordination, three studies were performed. The first study examined differences in articulatory variability in the onsets of word pairs such as cop top and top top. To this end, different phonetic contexts and speaking rate were manipulated. As word pairs like top top are frequently used as control stimuli and word pairs like cop top as experimental stimuli, this study investigated how these two word pairs differ in movement control. The second study examined how constraints on individual articulators, manipulated by phonetic context, and speaking rate affected the number of intrusions and reductions. The third study investigated how these intrusions and reductions were influenced by the presence or absence of auditory information. Movements of the tongue tip, tongue dorsum and lower lip were recorded with electromagnetic articulography. The first study revealed that word pairs with alternating and identical onset consonants differ to such an extent that using identical onset word pairs as control stimuli is not recommended for future error studies. The second study revealed that articulatory constraints resulted in asymmetrical patterns of intrusions: compared to a high back vowel context, a low vowel context resulted in more intrusions in general. In addition, in a front vowel context, the tongue dorsum intruded more frequently than the tongue tip and lower lip. The third study showed that speakers made fewer intrusions without auditory information available than with auditory information available. The results, which are explained within the framework of Articulatory Phonology and Task Dynamics, support the notion that articulatory constraints and auditory information influence coupling strength and movement coordination as reflected in intrusion and reduction patterns.Ph.D