# 3D-Printed Helmet for Electromagnetic Articulograph Applied in the Study of Oral Physiology
## 3 Results  
A total of 29 recordings were conducted with and without the helmet. Table 1 provides a summary of the results obtained.  
Figure 7 shows the frequency diagram of number of HC procedures performed in each recording session with the sensors placed on the subject's skin (S) and those placed on the helmet (H). Twenty (69%) sessions with the reference sensor on skin required only one HC, four (14%) required two and three HC, and one (3%) required four HC. When sensors were placed on the helmet, 23 (79%) required 1 HC, 5 (17%) sessions required 2 HC and 1 (3%) required 3 HC. The descriptive measures for each group were as follows: in the group without the helmet, the median was 1.5 (range: 1-4), while in the group with the helmet, it was 1.2 (range: 1-3). No statistically significant differences were found between the groups (\(p\) > 0.05). Figure 8 shows a violin graph summarizing these data.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Reference Sensors** & **N** & **HC** & **Mean** & **SD** & \(p\) \\
**Placement** & & & & & \\ \hline Skin & 29 & 44 & 1.5 & 0.87 & \\ Helmet & 29 & 36 & 1.2 & 0.51 & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Number of head corrections for group with reference sensors on skin and on helmet.  
Figure 7: Frequency diagram with number of head correction procedures performed in sessions with sensors on skin (S) and attached to helmet (H).  
No significant differences were found when comparing Session 1 and Session 2 between the group that used the helmet and the group with sensors adhered to the skin (Table 2).  
The number of head corrections performed in sessions 1 and 2 was compared across all participants, regardless of group assignment. This analysis aimed to evaluate potential variability between sessions. Significant differences were found between the recording sessions (Table 3).  
When the variation between sessions was analyzed in both groups, no significant differences were found. For this analysis, data from participants who completed both sessions were used (Table 4).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Reference Sensors** & **Session** & **N** & **HC** & **Mean** & \(p\) \\ \hline \multirow{2}{*}{Skin} & 1 & & 18 & 1.50 & \multirow{2}{*}{\(>\)0.05} \\  & 2 & 12 & 15 & 1.25 & \\ \hline \multirow{2}{*}{Helmet} & 1 & & 13 & 1.18 & \multirow{2}{*}{\(>\)0.05} \\  & 2 & 11 & 11 & 1.00 & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Number of head corrections for the subjects that performed both sessions.  
Figure 8: Violin graph with number of head correction procedure realized in sessions with sensors on skin (S) and attached to helmet (H). Squares point mean value.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Session** & **N** & **HC** & **Mean** & \(p\) \\ \hline
1 & 35 & 54 & 1.54 & \multirow{2}{*}{0.02 *} \\
2 & 23 & 26 & 1.13 & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Number of head corrections performed in sessions 1 and 2.  
Finally, a comparison was made against the ideal value of one head correction per session (Table 5). For both groups--sensors attached to the skin or to the helmet--Session 1 showed a value significantly different from 1. In contrast, in Session 2, neither group showed a significant difference from 1.