Surveys have shown that noise from wind turbines is perceived as annoying by a proportion of residents living in their vicinity, apparently at much lower noise levels than those inducing annoyance due to other environmental sources. The aim of the present study was to derive the exposure-response relationship between wind turbine noise exposure in L(den) and the expected percentage annoyed residents and to compare it to previously established relationships for industrial noise and transportation noise. In addition, the influence of several individual and situational factors was assessed. On the basis of available data from two surveys in Sweden (N=341, N=754) and one survey in the Netherlands (N=725), a relationship was derived for annoyance indoors and for annoyance outdoors at the dwelling. In comparison to other sources of environmental noise, annoyance due to wind turbine noise was found at relatively low noise exposure levels. Furthermore, annoyance was lower among residents who received economical benefit from wind turbines and higher among residents for whom the wind turbine was visible from the dwelling. Age and noise sensitivity had similar effects on annoyance to those found in research on annoyance by other sources.

A new approach for an airport noise monitoring system is presented that comprises not only a number of measuring stations, but also a dedicated sound propagation model and an aircraft noise emission model. This approach enables estimation of noise levels in the whole area around the airport and not only at the location of the measuring stations. An additional advantage is that the locations of the measuring stations can be chosen more freely. Traditionally the measuring stations must be located near residential areas where the influence of other noise sources (such as cars or wind) cannot be eliminated. Better locations can be found that yield more reliable data and therefore more reliable noise levels. To update the sound propagation model frequently, the measuring stations not only measure noise levels, but also other parameters, like temperature and wind profile. The sound emission of the aircraft is derived from measurement results, complemented with a directional aircraft noise emission model. A tool was developed to visualize the power of combining data and models in this model-based monitoring system. The use of models opens possibilities for interesting applications such as i) short term noise forecasts, ii) scenario studies with various aircraft distributions and iii) enforcement of noise limits.

The noise reduction of a (low) barrier can be enhanced by using an additional element with quarter-wavelength resonators with varying depths. A so-called Whiswall or WHIStop deflects sound upwards for specific frequencies. Measurements for a 1.1 meter high Whiswall and for a 1.1m barrier are compared in a separate paper. The enhanced barrier effect is measured at a short distance behind the barrier, for several situations. In this paper these measurements are compared with the results of a numerical finite element model (FEM) to validate this model. Next, the noise reduction is calculated at long ranges, up to 600 meters, for different point-to-point scenarios representative for road and rail traffic. A numerical parabolic equation method (PE) is coupled to the FEM model and a representative downwind condition is taken into account. The results at longer distance are used to design an engineering method for the enhanced barrier effect that can be used in standard noise calculation models, such as the Dutch national calculation model (SRM2) or the ISO 9613-2 standard.

Action Plans for the reduction of the number of people harmfully affected by environmental noise. TNO is developing a decision support system for noise mitigating measures. The proof of concept of such a system for road noise is presented here. On the basis of a detailed noise map, for each road segment an indication is given for the amount of negative effect (e.g. number of people being highly annoyed) per meter it is causing. On the basis of the characteristics of the road segment, the system suggests possible noise mitigation measures. The effect of the measure chosen by the user, such as the application of silent road surface types or lowering speed limits, can be interactively explored with the system. It directly shows the updated detailed noise contour maps as well as indicators describing the impact after a measure has been applied though the interactive interface.

No abstract