Improvement of measurement accuracy for the three-dimensional electromagnetic articulograph by optimizing the alignment of the transmitter coils

Abstract

The alignment of transmitter coils for the three-dimensional electromagnetic articulograph (3D-EMA), an instrument used to measure articulatory movements, was studied. Receiver coils of the 3D-EMA are used as position markers and are placed in alternating magnetic field produced by multiple transmitter coils. The estimation of the state (the position and orientation) of each receiver coil is based on the minimization of the signal error between the measured and predicted receiver signals using a model of the magnetic field. Previous studies report a noticeable increase in the position estimation error irrespective of small signal error at a specific portion of the measurement region. The existence of the non-uniqueness problem in the position estimation is hypothesized to be the cause of this problem. To resolve the problem, we optimized the alignment of the transmitter coils by maximizing the difference between the receiver signals for any pair of states in the measurement region and evaluated the alignment by performing computer simulations and actual measurement. As a result, a measurement accuracy of approximately 0.4 mm was obtained.

Discrete Anatomical Coordinates for Speech Production and Synthesis

“…The state of the art of the techniques used to monitor the articulatory movements during speech remained stagnant during the last decades, with some exceptions employing different technologies to measure the different articulators (Bouchard et al, 2016). The standard method used to track the articulator's displacements during speech is the EMA (Schönle et al, 1987;Uchida et al, 2014). This technique provides very accurate recordings (Goozée et al, 2000;Engwall, 2003;Steiner et al, 2013) at the expenses of being non portable and expensive.…”