## 2 Materials and Methods
### Design of Simulation
#### 2.1.5 Graphical User Interphase (GUI)  
A graphical user interface (GUI) was developed to enhance the usability of the simulation tool. This interface integrates pre-processing and post-processing code into a user-friendly platform. This interface simplifies the simulation process, making it more accessible for users. Before the GUI construction, a preliminary layout design was created to delineate input and output components, serving as a reference for the final design.  
The input section includes components for file import, receiver location specification, and sound source configuration. The output section provides safety recommendations, the resultant Sound Pressure Level (SPL), and a clear indication of whether the SPL exceeds established safety limits.  
The GUI is organised into five sections, as illustrated in Figure 3: floor plan, receiver, sound source, safety recommendations, and output. The floor plan section features a button  
\begin{table}
\begin{tabular}{c c} \hline
**Material** & **Sound Absorption Coefficient** \\ \hline Perfect reflector & 0 \\ \hline Plasterboard & 0.29 \\ \hline Ceiling Board & 0.25 \\ \hline Chipboard & 0.20 \\ \hline Floorboard & 0.25 \\ \hline Concrete & 0.02 \\ \hline Brick & 0.08 \\ \hline Wood & 0.35 \\ \hline Glass & 0.03 \\ \hline Metal & 0.01 \\ \hline \end{tabular}
\end{table}
Table 1: Materials with their respective properties.  
for users to upload the factory layout intended for evaluation. The GUI Section 2 allows for the definition of the receiver's location within the layout. The GUI Section 3 is dedicated to inputting the sound sources, where users can specify the location and SPL of each source. GUI Section 4 presents safety recommendations if the resultant SPL surpasses the allowable limits, while GUI Section 5 displays all pertinent output data, ensuring users can easily interpret the simulation results.  
With the GUI design completed, the final step involves integrating the pre-processing and post-processing components with the interface to create a fully functional application. The resultant Sound Pressure Level (SPL) is displayed on the GUI using a gauge, giving users a visual representation of the noise levels. This resultant SPL is then utilised in calculations for the maximum allowable exposure time and the minimum Noise Reduction Rating (NRR) for ear protection, with these values also presented on the GUI. A reset button was also implemented to restore all values to their initial settings, allowing users to restart the simulation process seamlessly. Figure 4 illustrates a scenario where the resultant SPL exceeds the permissible limit.  
In the yellow section of Figure 4, safety recommendations are automatically generated based on the resultant SPL, which is compared against Malaysian safety standards. The application provides suggestions for managing noise exposure, including calculating the maximum allowable exposure time and the minimum NRR required for ear protection over an 8-hour work shift. The maximum exposure time indicates a worker's duration in a specific location during a single workday, emphasising the need to consider other daily noise exposures. Conversely, the minimum NRR rating indicates the least adequate ear protection a worker must utilise to mitigate risk while working in that location for an 8-hour shift. This integration of safety features enhances the application's functionality, promoting a safer working environment.  
Figure 3: Sections in the graphical user interface (1—file upload, 2—receiver information, 3—source information, 4—safety recommendations, and 5—resultant SPL).