In spite of existing European and national legislation aimed at noise abatement, public interest and concern about noise are high. The EU Directive 70/157/EEC [15] for setting and controlling environmental noise is aimed at creating less noisy and more pleasant environment for European residents within "Sustainable Development in Europe". The authors are presenting a methodology for measuring selected acoustic descriptors (sound absorption coefficient and sound transmission loss) for acoustic materials, which are currently in process of development. Emphasis is put on sandwich structures of absorbers. Verification results of the proposed methodology are presented.
In terms of design and material composition, cars are the large set of diverse materials and raw materials. The relative proportion of materials varies along with the development and innovation of new types of cars. The most represented material is metal. On average, outdated cars feature about 8% of plastic and approximately 4% of rubber products. The problem is the further use of these recycled materials. The research has found new areas for the use of tires, waste foam and interior materials—noise reduction. The authors have designed and tested several variations of acoustic absorption materials. Of the tested materials, the best parameters were shown by “ecofoam”—almost across the entire frequency range (100–5000 Hz).
Sound and noise are as old as humanity itself. They have accompanied civilization, evolution, and development for centuries. Music and speech represent not only the key elements of human life but also unpleasant feelings of noise that have always been an integral part of human existence. As industrial development has required more energy, powerful machinery, and equipment, there have been still noisier machines. Traffic has grown quickly due to the number and speed of vehicles. For that reason, an acoustic camera is used for the dynamic visualization of machinery and equipment noise as it analyses the sources of noise in details. Subsequently, qualified measures are introduced based on the results of the analysis. The paper considers launching another application. According to the proposed methodology, its use in identifying machinery and equipment failures and their maintenance is proved. The experiment was performed on a four-wheel lawn mower. The primary focus was on the identification of failures using an acoustic camera. The previous method allowed to quickly, precisely and efficiently identifying the failures in two out of five tested machines.
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