Articulatory space calibration in 3D Electro-Magnetic Articulography

This paper introduces a new method to calibrate data collected using Electro-Magnetic Articulography (EMA) into an appropriate articulatory space. A bite plate record for a target subject is used to define the maxillary occlusal and midsagittal planes, and then a single quaternion rotation is derived to transform the dataset into the new anatomically referenced space. The choice of specific rotation solution is discussed relative to the corresponding anatomical assumptions regarding the original sensor placement and coordinate system. Data were collected using NDI Wave Speech Research System for one pilot subject, and calibration results and consistency throughout the calibration record reviewed. The results show that the rotation solution can accurately and consistently transform all sensors´ positions into an articulatory space in which sensor movements and orientations can be easily analyzed. This preliminary study enables the investigation of articulatory kinematics and relationship to acoustics.