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This paper presents a three-dimensional mathematical model which characterizes the variation of sound pressure level propagation and the variation of attenuation of the sound pressure level propagated in an enclosed space. The variable taken into consideration both in the experiments and in the mathematical modeling were: the positions of the acoustic screen to noise source; the height of the microphone to record the sound pressure level for a variable number of walls. The mathematical model is based on the experimental data obtained in laboratory, using an experimental setup, which comprises a variable number of walls as acoustic screen.

The workplace accidents are considered major sources of risk in the term of occupational safety. In these sense the employers take in consideration the workplaces risks plans. Risk workplace assessments allows employers to ensure preventive plans to limit or eliminate the risk factors by: selection of adequate working conditions, limited risk exposure, implementation of the proper individual safety equipment's, periodical medical inspection, ergonomic workplace design. The current paper presents the results of the occupational risk assessment at the level of the Faculty of Engineering within the "Vasile Alecsandri" University in Bacau. The assessment was conducted by applying the method developed by the National Institute of Research and Development for on Labour Protection, Bucharest. Risk assessment enables the identification of risk factors from analysed system, for the each risk factor, by components: production equipment's, workplace conditions, type of work, work performer as well the risk reduction and prevention. The overall risk level calculated varies between 2.69 and 3.10. The distribution of risk factors by generating sources indicated, for all jobs, as principal risk factor the work resources. The second risk factor was specific for the performer and workplace and the last was work task risks factors.

This paper presents a set of software for prediction, calculation and noise mapping. These are useful both in assessing noise and adopting practical measures in order to reduce noise in areas with intense traffic. The software, through their working tools, allows making comparisons concerning noise before and after implementing noise reduction measures. The analyzed software's of noise prediction, calculation and mapping are specialized for noise generated by traffic.

There is an extensive literature covering a number of considerations for installing noise barriers to protect living areas. In fact, noise barriers are the most popular mitigation measure on major roads across Europe. This paper aims to review some situations where the use of noise barriers is not fully recommended. Fortunately, there are available wide ranges of technical noise solutions as an alternative to the barriers. What we propose in this article is to create a simple procedure to help decision makers to decide if noise barrier is the best option for noise mitigation case by case. For this, we tested some alternatives through checking the acoustic performance of "ultra-quiet" pavement like PERS (Porous Elastic Road Surface), and a combination of speed reduction with other more common quiet pavement (in this case thin layer). The results have shown that the installation of PERS is one of the most promising solutions because, as all measures were taken on the noise source, reduces noise everywhere, but PERS does it in an impressive manner. Although its acoustic properties remain good over time, the negative part of PERS is its low durability that makes increase its installation costs by having to replace it too often. The paper, in addition to efficiency and cost, analyzes the criterion of visual impact that should be part of suitability analysis of any noise barrier construction.