Purpose: Functional orofacial behaviors vary in their force endpoint and rate of recruitment. This study assessed the gating of orofacial cutaneous somatosensation during different cyclic lip force recruitment rates. Understanding how differences in the rate of force recruitment influences trigeminal system function is an important step toward furthering the knowledge of orofacial sensorimotor control.

Method: Lower lip vibrotactile detection thresholds (LL-VDTs) were sampled in response to sinusoidal inputs delivered to the lip vermilion at 5, 10, 50, and 150 Hz while adult participants engaged in a baseline condition (no force), 2 low-level lip force recruitment tasks differing by rate (0.1 Hz or 2 Hz), and passive displacement of the lip as a control to approximate the mechanosensory consequences of voluntary movement.

Results: LL-VDTs increased significantly for test frequencies at or below 50 Hz during voluntary lip force recruitment. LL-VDT shifts were positively related to changes in the rate of lip force recruitment, whereas passively imposed displacements of the lip were ineffective in shifting LL-VDTs.

Conclusions: These findings are considered in relation to published reports of force-related sensory gating in orofacial and limb systems and the potential role of somatosensory gating along the trigeminal system during orofacial behaviors.

Purpose: Previous research has found that auditory training helps native English speakers to perceive phonemic vowel length contrasts in Japanese, but their performance did not reach native levels after training. Given that multimodal information, such as lip movement and hand gesture, influences many aspects of native language processing, the authors examined whether multimodal input helps to improve native English speakers' ability to perceive Japanese vowel length contrasts.

Method: Sixty native English speakers participated in 1 of 4 types of training: (a) audio-only; (b) audio-mouth; (c) audio-hands; and (d) audio-mouth-hands. Before and after training, participants were given phoneme perception tests that measured their ability to identify short and long vowels in Japanese (e.g., /kato/ vs. /katoː/).

Results: Although all 4 groups improved from pre- to posttest (replicating previous research), the participants in the audio-mouth condition improved more than those in the audio-only condition, whereas the 2 conditions involving hand gestures did not.

Conclusions: Seeing lip movements during training significantly helps learners to perceive difficult second-language phonemic contrasts, but seeing hand gestures does not. The authors discuss possible benefits and limitations of using multimodal information in second-language phoneme learning.

Purpose: One popular method to study the motion of oral articulators is 3D electromagnetic articulography. For many studies, it is important to use an algorithm to decouple the motion of the tongue and the lower lip from the motion of the mandible. In this article, the authors describe and compare 4 methods for decoupling jaw motion by using 3D tongue and lower lip data.

Method: A 3D position estimation method (3DPE), an adapted version of the estimated rotation method (ERM) proposed by Westbury, Lindstrom, and McClean (2002) for 3D recordings, a linear subtraction method, and a new method called Jaw and Oral Analysis (JOANA) were evaluated with data recorded from sensors attached to the lower molars, lower lip, and tongue.

Results: The 3DPE method showed the fewest errors. However, unlike the other methods, it requires more than one sensor attached to the lower jaw. Among the single-sensor methods, JOANA was found to be the most comparable to 3DPE.

Conclusion: The findings suggest that JOANA is efficient in decoupling tongue and lower lip motion from jaw motion, whereas ERM, with its less complicated procedure for attaching the lower jaw incisor sensor, can be considered a viable alternative.