Reliability of electromagnetic midsagittal articulometry and electropalatography data acquired simultaneously

Abstract

This study evaluates the effects on electromagnetic midsagittal articulometry (EMA) coils from electrode activation on an electropalatography (EPG) artificial palate, and on EPG contact patterns induced by EMA coils. In order to investigate the first issue, five transducer coils on a fixed magazine were placed equidistantly among themselves and with respect to the three transmitter coils of an EMA helmet. Two palate positions were used, i.e., perpendicular to the magazine (to emulate possible effects on coils placed on the nose, upper incisors, jaw, and lips) and parallel to it (to imitate effects on coils placed on the tongue surface). A thin leaf of aluminum firmly pressed by a mold was used to create contact activation. Data for different degrees of contact activation were subtracted from data obtained with no artificial palate (perpendicular condition) or with an artificial palate with zero ‘‘on’’ electrodes (parallel condition). Only for the most extreme condition, i.e., a high degree of contact activation and a short coil-to-artificial palate distance, do the effects slightly exceed the noise level for the EMA equipment. The analysis of the second issue was carried out for coils attached to the tongue tip, the tongue blade, and the tongue dorsum during the production of several consonants. Coil-to-lingual contact effects occur mostly near the midline of the artificial palate at different locations, depending on the degree of contact and the location of the consonant.