**3.4 Challenges in developing countries in the field of environmental noise modeling, mapping, and monitoring and guidelines to overcome them**

Environmental noise modeling has the objective to estimate national and local equivalent noise sound pressure levels in terms of L90, L10, Lmax, Lmin and Leq. The result of noise modeling may be used for the development of two-dimensional (2D) and three-dimensional (3D) noise maps which provide information on noise exposure of people [44, 45]. Noise monitoring is used to assess critical sound pressure levels in residential, commercial, and industrial areas under different environmental conditions. In addition, noise monitoring can serve to validate and/or verify noise modeling predictions, and to establish and/or strengthen national and local sound pressure level monitoring programmes [46–51].

In developing countries, the 'challenges' for noise modeling and mapping are the lack of [13, 52, 53]:


For noise monitoring, the challenges for developing countries include:

	- Coverage and/or limited coverage of outdoor sound pressure level monitoring systems.
	- Periodic review of sound pressure level monitoring issues.

'Guidelines' for overcoming main challenges of environmental noise modeling, mapping, and monitoring include [16, 19]:

• Sound propagation models are useful to determine the extent and spatial coverage of noise from different sources. Propagation models can provide estimates of sound pressure levels from transportation, ports and airports, railways, and industrial plants.

