Five-dimensional articulography

This chapter reviews current developments in the use of five-dimensional electromagnetic articulography for speech research. Obvious advantages are higher information density per sensor (three Cartesian coordinates, two spherical coordinates) compared to traditional 2D EMMA systems, and the removal of the necessity to constrain the subject's head. The drawbacks are equally related to this higher dimensional space: position calculation involves solving a non-linear optimization problem. In some cases, unstable solutions are encountered, resulting in mistrackings. The chapter illustrates how the higher information density allows particularly succinct and robust characterizations of tongue configuration. Discussion also focuses on monitoring of head movement. This is crucial for accurate recovery of articulator movements themselves, but is also intrinsically interesting as part of speech motor activity. In addition to improving the naturalness of the speaking situation, the freedom of head movement also means that subjects tolerate longer recording sessions. This can facilitate new experimental paradigms.