Noise control by sonic crystal barriers made of recycled materials

A systematic study of noise barriers based on sonic crystals made of cylinders that use recycled materials like absorbing component is here reported. The barriers consist of only three rows of perforated metal shells filled with rubber crumb. Measurements of reflectance and transmittance by these barriers are reported. Their attenuation properties result from a combination of sound absorption by the rubber crumb and reflection by the periodic distribution of scatterers. It is concluded that porous cylinders can be used as building blocks whose physical parameters can be optimized in order to design efficient barriers adapted to different noisy environments

Evaluation of annoyance from the wind turbine noise: A pilot study

Objectives: The overall aim of this study was to evaluate the perception of and annoyance due to the noise from wind turbines in populated areas of Poland. Material and Methods: The study group comprised 156 subjects. All subjects were asked to fill in a questionnaire developed to enable evaluation of their living conditions, including prevalence of annoyance due to the noise from wind turbines and the self-assessment of physical health and well-being. In addition, current mental health status of the respondents was assessed using Goldberg General Health Questionnaire GHQ-12. For areas where the respondents lived, A-weighted sound pressure levels (SPLs) were calculated as the sum of the contributions from the wind power plants in the specific area. Results: It has been shown that the wind turbine noise at the calculated A-weigh­ted SPL of 30-48 dB was noticed outdoors by 60.3% of the respondents. This noise was perceived as annoying outdoors by 33.3% of the respondents, while indoors by 20.5% of them. The odds ratio of being annoyed outdoors by the wind turbine noise increased along with increasing SPLs (OR = 2.1; 95% CI: 1.22-3.62). The subjects' attitude to wind turbines in general and sensitivity to landscape littering was found to have significant impact on the perceived annoyance. About 63% of variance in outdoors annoyance assessment might be explained by the noise level, general attitude to wind turbines and sensitivity to landscape littering. Conclusions: Before firm conclusions can be drawn further studies are needed, including a larger number of respondents with different living environments (i.e., dissimilar terrain, different urbanization and road traffic intensity)

Effects of built environment morphology on wind turbine noise exposure at building façades

© 2017 Elsevier LtdWith wind farms installed in urban and suburban areas, the noise exposure of buildings is affected both by distance attenuation and the morphology of the built environment. With the aim of exploring the noise-resisting effects of built environment morphology, three kinds of typical suburban areas in the UK were sampled and noise maps were generated based upon an idealised modern wind turbine placed at various setback distances from each site. Relationships between morphological indices and building façade exposures were examined through regression analyses. Noise reduction levels of five morphological indices were given in terms of resisting wind turbine noise with different source-receiver (S-R) distances, and at different frequencies. The results show that built environment morphology has considerable effects on resisting the noise exposure of buildings and can create a quiet façade with up to 13 dBA difference to the most exposure façade. Among the five indices, building orientation is found to be most effective in resisting the noise exposure of building façades, followed by the length and shape of the building. The noise resistance effects vary by different S-R distances and differ by frequency. Four morphological indices are found to be effective in resisting noise at low frequencies, typically at 50 Hz

Towards a general framework for including noise impacts in LCA

Industrial Ecolog

Aperiodicity effects on sound transmission through arrays of identical cylinders perpendicular to the ground

Results of laboratory measurements of sound transmission through 5 × 10 arrays of meter long polyvinyl chloride pipes with lattice constants of 5 and 10 cm with filling fractions of 13% and 50% located either on medium density fibreboard or a layer of felt are reported. Ground effects and sonic crystal effects are found to be additive. Measurements and predictions show that, while there is little broadband advantage in a periodic configuration compared with a random one, a quasi-periodic arrangement in which the perturbation has a standard deviation equal to the scatterer diameter gives the best overall attenuation