## 3 Methods
### Setup and Equipment  
The study occurred in a clinic at the medical city. To test verbal interactions, we used Alexa on a cell phone, primarily because it supported the Arabic language and all participants were Arabic speakers. To test nonverbal voice interactions, we employed the Daria system. Finally, to test eye gaze interactions, we used Tobii Eye Tracker 4C, an off-the-shelf eye tracker from a leading eye tracking company [52]. Tobii Eye Tracker 4C is compatible with Windows PCs and easy to use. The tracker was magnetically affixed to the bottom of the laptop screen. For the eye tracking interactions, the key components were the eye tracker device and a HTML web page containing buttons, each of which represented a command. This page was connected to Raspberry Pi through the RabbitMQ message broker. The user interface of this HTML page was designed in accordance with guidelines that recommended large buttons to ensure ease of selection and interaction [53].  
During the study, participants were asked to instruct the devices to perform five tasks: turn on the lights, play music, play the news, call someone, and ask about the weather. These tasks were selected because they were the most commonly used by individuals who had dysarthria, as indicated in [15]. First, participants verbally asked [PERSON] to perform these five tasks. The order of the tasks was randomized and varied for each participant.  
Next, participants switched to Daria and gave commands using nonverbal voice cues. Given that participants were less familiar with this system, we provided a brief description of Daria and introduced the commands for the expected actions (the same as those for Alexa).  
Finally, participants tested the eye gaze system. When they used the eye tracker, a bar containing buttons appeared at the top of the screen, as shown in Figure 1. A red circle, functioning as a cursor (see Figure 1), also appeared, positioned on the second item from the left on the bar, which participants controlled using their eyes. Participants were instructed on how to use the tracker, including identifying which buttons represented the left-click mouse function and confirm button. The users were required to select the mouse click button through dwell time. Once this bar disappeared, they needed to use the cursor (see Figure 2) to choose one of the boxes, each of which represented a command, that appeared on the screen. Once the user pointed to one of the boxes, it was highlighted, and the action was performed.  
After each of the three parts, participants completed the SUS and the NASA-TLX questionnaire. Following completion, post-study interviews were conducted to ask about their preference among the three systems.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Participant** & **Gender** & **Severity** & **Age Range** & **Diagnosis** \\ \hline P1 & Male & Mild & 25–44 & Traumatic brain injury \\ P2 & Male & Mild & 45–65 & Stroke \\ P3 & Female & Mild & 25–44 & Cerebral palsy \\ P4 & Male & Moderate & 45–65 & Spinal cord injury \\ P5 & Male & Moderate & 25–44 & Traumatic brain injury \\ P6 & Male & Severe & 25–44 & Stroke \\ P7 & Male & Severe & 25–44 & Traumatic brain injury \\ P8 & Male & Severe & 18–24 & Traumatic Brain Injury \\ \hline \end{tabular}
\end{table}
Table 1: Participants details.