## 2 Materials and Methods
### Design of Simulation
#### 2.1.3 Pre-Processing Section  
Before initiating the coding process, all necessary formulas are encapsulated as distinct functions, simplifying and clarifying subsequent coding steps. The backend code begins with plotting of sound sources (transmitters) and receiver points onto the floor plan. Following this, the propagation model is configured, enabling the execution of the ray tracing algorithm. Each generated ray is calculated individually, accounting for distance travelled and interactions with reflective surfaces. Subsequently, the SPL for each ray is computed, and these values are integrated to yield a cumulative SPL at the receiver location. Before practical implementation, it is essential to validate the simulation's assumptions and integrity. This validation process includes comparative analyses involving multiple simulation runs, theoretical formulas, and external data sources, including real-world measurements. This step is critical for assessing the reliability of the simulation outputs for real-world applications. Initially, simulation variables are rigorously tested, followed by comparing simulation results against manual calculations to confirm accuracy and applicability. The MATLAB ray tracing engine generates all possible ray paths between the transmitter and receiver, incorporating reflections from surfaces and applying the inverse square law to determine the resultant Sound Pressure Level (SPL). A sound source and receiver are positioned within the same floor plan for initial testing, with a fixed separation of 20 m. All parameters are set as previously specified, except for the maximum number of reflections. The reflection count is initially set to zero to facilitate direct comparison, allowing only a single direct ray path for the verification stage. Once the direct transmission is validated, reflections are incrementally introduced, and the results are compared to manual calculations to ensure consistency and accuracy in the model. The number of reflections significantly impacts the resultant SPL. Reflections continue indefinitely until the sound energy dissipates; however, after a certain number of reflections, the energy becomes too minimal to affect the outcome meaningfully. Increasing the reflection count also demands more computational power, which can slow down processing. Therefore, identifying an optimal reflection count, where additional reflections produce negligible changes in SPL, is essential. This is achieved by conducting simulations with fixed variables, incrementally increasing the reflection count from zero until further increases have an insignificant effect. For this analysis, two sound sources and one receiver are used, with results tabulated and graphed to illustrate the influence of reflections on SPL. Surface material properties are also integral to the simulation, with material types specified as 'plasterboard', 'perfect reflector', 'ceiling board', 'chipboard', 'floorboard', 'concrete', 'brick', 'wood', 'glass','metal', 'water','vegetation', 'loam', or 'custom'. The material type affects reflection loss calculations where rays intersect surfaces. When set to 'custom', properties like permittivity and conductivity are defined in the 'Surface Material Permititivity' and 'Surface Material Conductivity' fields. Materials such as water, vegetation, and loam are excluded, as they are beyond the scope of this industrial setting. Table 1 provides an overview of all materials included in the simulation, alongside their respective properties. A controlled test is conducted to evaluate the impact of varying surface materials on the resultant Sound Pressure Level (SPL). In this experiment, all variables are held constant, with the sole exception being the surface material. This approach systematically compares SPL outcomes, providing insights into how different materials influence sound propagation. The test involves using two sound sources positioned with a single receiver within the designated floor plan, enabling a thorough assessment of the material effects on the SPL.