The effect of phonetic context on the dynamics of intrusions and reductions

Recent studies have described speech errors as articulatory movements intruding during target constrictions as well as reduced movements of these target constrictions. These errors were hypothesized to originate from self-organizing mechanisms underlying context-free gestural coordination. The current study investigates whether such self-organizing mechanisms and resulting speech errors are influenced by coproduction constraints, which are introduced by phonetic context. Speakers repeated CVC-CVC word pairs, differing in onsets and sharing their rhymes. “Phonetic context” was manipulated by changing the rhyme across different word pairs using specific vowel- and consonant-combinations. Vertical movements of tongue tip, tongue dorsum, and lower lip were recorded with Electro-Magnetic Articulography. The results revealed that the tongue dorsum as an intruding articulator showed more intrusions in front vowel context than in low back vowel context. In addition, this articulator showed more intrusions than the tongue tip in /æ/ context, and more intrusions than the lower lip in /ɪ/ context. Reductions did not demonstrate this effect of vowel context. However, both tongue dorsum and tongue tip reduced more than the lower lip. The findings are explained in terms of the amount of spatial overlap of gestures and intruding articulatory movements, as defined in Articulatory Phonology.