Effect of phonetic onset on acoustic and articulatory speech reaction times studied with tongue ultrasound

We study the effect that phonetic onset has on acoustic and articulatory reaction times. An acoustic study by Rastle et al. (2005) shows that the place and manner of the first consonant in a target affects acoustic RT. An articulatory study by Kawamoto et al. (2008) shows that the same effect is not present in articulatory reaction time of the lips. We hypothesise, therefore, that in a replication with articulatory instrumentation for the tongue, we should find the same acoustic effect, but no effect in the articulatory reaction time. As a proof of concept of articulatory measurement from ultrasound images, we report results from a pilot experiment which also extends the dataset to include onset-less syllables. The hypothesis is essentially confirmed with statistical analysis and we explore and discuss the effect of different vowels and onset types (including null onsets) on articulatory and acoustic RT and speech production.