Noise map

Computation methods are widely preferred, because of the large amount of yearly averaged locations required.

[citation needed] Using either approach, a grid of receivers must be defined in order to measure or calculate noise levels.

When results are obtained, using GIS tools, spatial interpolation must be applied in order to give a continuous graphical representation of sound levels.

Today the use of software packages has made the process easier, but the accuracy of results depends on the quality of input data.

For train and road traffic noise, the description of the sources is usually made in terms of parameters such as speed, number of vehicles etc.