Alice Elizabeth González

By Alice Elizabeth González

Part of the book: Noise Control, Reduction and Cancellation Solutions in Engineering

By Alice Elizabeth González

Acoustic quality of closed spaces is an increasing concern all around the world, since noise pollution is one of the main nowadays pollutants, but also one of the less considered when building designing and construction. In 2011, the World Health Organization stated that noise pollution should be treated as a public health concern: about 1 million years of human healthy life are lost yearly because of the environmental noise pollution, emphasizing on traffic noise in the cities. There are some physics phenomena that are the rule of thumb for room acoustic projects. This chapter introduces the main concepts about them: sound absorption, insulation, and diffusion. Their principles, main implementation, and computing are presented for each one.

Part of the book: Acoustics of Materials

By Alice Elizabeth González and José Cataldo Ottieri

The prediction of the environmental sound pressure levels of wind farms does not yet have a global consensus on how to achieve an easy-to-build model with accurate results. This chapter aims to present the sound pressure level prediction model developed at Universidad de la República (Uruguay). Its main characteristics are: taking into account atmospheric stability to determine the acoustic power of the machines; describing the generation of noise along the blades due to turbulent phenomena; and calculating the noise propagation at different distances from the tower taking into account atmospheric absorption, turbulence energy dissipation, and geometric divergence. It does not have any special IT requirements. A new approach to calculating geometric divergence is considered. The results show more than 80% of the cases within the range of ±3 dB, for wind farms throughout our country. The need to use not only A-weighted sound pressure levels but also octave frequency band levels is indicated.

Part of the book: Wind Turbines

By Alice Elizabeth González

Noise control refers to a set of methods, techniques, and technologies that allows obtaining acceptable noise levels in a given place, according to economic and operational considerations. The question of “acceptance” is for what or for whom. Generally, there is no single answer to this question, nor is there a single solution to any given problem, as long as regulatory compliance is achieved. Noise control does not necessarily imply the reduction of noise emissions—it refers to making acceptable sound pressure levels of immission (i.e., the signal reaching the receiver). This chapter aims to present the basis of noise control techniques, both in emission and propagation, to finally achieve the most current protection techniques for the receivers, when there are no more alternatives in the previous steps.

Part of the book: Noise Control

By Martha Cobo Dorado, Gissell Rodríguez Milan and Alice Elizabeth González

In this chapter, a case study is presented on the evaluation of acoustic performance of a tree barrier. It is a eucalyptus barrier that was planted as a visual barrier to block an industrial plant. First, the depletion law of sound pressure levels (SPL) of the source was analyzed; a linear divergence was found. A calculation scheme similar to that of ISO 9613-2 was applied. When comparing the SPL measured at a specific receiver with the results of propagating the SPL from the source without considering the existence of the barrier, an extra attenuation of 12 dB appeared, reinforcing the idea that the plantation behaves as an acoustic barrier. Four different calculations were used to obtain its insertion loss (IL), including general equations and expressions developed for green barriers. The best fit was obtained using equations for solid barriers, although it was not the expected result. This finding could be explained by the great distance between the source and the receiver. It opens the possibility of successfully using IL prediction equations for solid acoustic barriers (both thin and thick) to estimate the acoustic performance of green barriers, at least under conditions similar to those of this case study.

Part of the book: Management of Noise Pollution