In this phase, users would select any 3D model they wish to analyze on, enable it as a sound source, and assign some characteristics of the sound source. The sound receiving plane can either be manually placed individually or automatically generated along the road. There is also a search feature if users need to look for a specific sound receiving plane inside the VR space.

▲Fig.1 Enabling as a Sound Source

▲Fig.2 Generating Sound Receiving Walls along the road

The Noise Simulation plugin provides a full range of options for both simple and complex simulations. Users can thus alternate between different levels of details to suit their own needs or objectives. Some of the main elements of the analysis are shown in the following:

1. For every sound emission routes, the numbers and sequences of sound refraction, reflection, penetration, and attenuation are identified and calculated.
2. The attenuation of sound pressure level subject to the linear distance between a sound source's position and a sound receiving plane.
3. A-weighting of the sound *A-weighting is the method of assigning a coefficient that offsets the collected sounds so that only those receivable by human ears are considered.
4. Synthesizing the sound pressure level frequency at every sound receiving plane.
5. Synthesizing the sound pressure level at a sound receiving plane if it is receiving noises emitted from multiple routes.
6. Equivalent continuous A-weighted sound pressure level analysis.

With a variety of display options, it is possible to view the simulation result from different perspectives. Other than the standard contour (line) maps, we have also added a grid-shaped map, as well as a sphere-shaped map to help visualize and understand the sound pressure level.

▲Fig.3 Contour visual map

▲Fig.4 Contour line visual map

▲Fig.5 Grid-shaped visual map

▲Fig.6 Sphere-shaped visual map

This option is unique due to the following reasons:

1. Takes into account of terrain and buildings placed in UC-win/Road
2. Sound source characteristics can be assigned in details, such as:
   - 2 lane road noise
   - compound noise from multiple sources (e.g. construction noise & road noise)
   - noise of some complicated movements
   - sound sources with acoustic level or frequency that is affected by time
3. Automatically generation of points or planes over where sound is received.

▲Consideration of position of sound
sources, and transmission routes.

Before starting, it is necessary to at least place, position, and define the sound sources, sound receiving points / planes.
Once the above is done, the plugin retrieves or generates the following information:

1. Retrieves the positional coordinates of terrain or building surfaces from UC-win/Road
2. Retrieves the positional coordinates and sound source characteristics from the sound source data as specified in UC-win/Road
3. Generates the positional coordinates of sound receiving points on the arbitrary plane(s) specified in UC-win/Road.

The following entries are entered into dialog boxes:

1. Parameter: ⊿t, number of sound emission routes, etc.
2. Sound Source Position: positional coordinates, property ID, applied start time, applied end time
3. Sound Source Characteristics：fundamental harmonic and its ID
4. Fundamental Harmonic: frequency, initial phase, half amplitude
5. Sound Receiving Point: positional coordinates, ID of the surface assigned

The following data is retrieved automatically from UC-win/Road.

1. Terrain and ground surface.
2. Road earthworks and pavement.
3. Normal models.
4. Road models.

The details of the calculations are written as follow:

1. For every sound emission routes, the numbers and sequences of sound refraction, reflection, penetration, and attenuation are identified and calculated.
2. The attenuation of sound pressure level subject to the linear distance between a sound source's position and a sound receiving plane.
3. A-weighting of the sound.
4. Synthesizing the sound pressure level frequency at every sound receiving plane.
5. Synthesizing the sound pressure level at a sound receiving plane if it is receiving noises emitted from multiple routes.
6. Equivalent continuous A-weighted sound pressure level analysis.

Results are outputted into the following:

1. Individual sound receiving point's sound pressure level and equivalent continuous A-weighted sound pressure level at the end time of the analysis (.csv file)
2. Individual sound receiving point's sound pressure level at all times (for generating time - sound pressure level graph).
3. Sound pressure level on an arbitrary plane at the end time of the analysis (for creating contour maps)

Based on the outputted data, the following graphs can be generated and displayed:

1. Time - sound pressure level graph.
2. Contour maps of sound pressure level. Displayed directly into UC-win/Road.

▲Time - sound pressure level graph

▲Contour maps of sound pressure level