## Solving external noise assessment tasks using low-cost commercial computer tools

Inge Hommedal
Kilde Akustikk AS
Tvildesvegen 16D
5700 Voss
Telefon: 909 32 527 (mobil/direkte)
Telefon: 47 47 85 00 (sentralbord)

inge.hommedal@kilde.no

This paper deals with the practical use of simple computer tools in assessing and mapping external noise. The process is divided into five main steps:

1. Evaluation of the external noise situation (e.g. road traffic noise, noise from railbound traffic, noise from wind turbines, shooting range noise).

2. Conditioning of input data using low-cost computer tools. The emphasis will be on topography and buildings.

3. Building the corresponding noise model in a computer tool.

4. Output data conditioning using low-cost computer tools.

5. Noise maps and other graphical presentations using a low-cost mapping tool.

The main output data from the noise model is regular or non-regular grids of computed dB-values. For noise mapping these grids must be interpolated in some way.

Different ways of such interpolations are discussed in some detail, showing typical variations and pitfalls.

The process is similar to the corresponding process using off-the shelf computer tools but the steps have to be done separately using stand-alone tools, yielding

a less automated but in some instances a more flexible and cost-effecive way to do the noise assessment tasks.