It is accepted that noise pollution has a major impact on health, such as physical, physiological, psychological and performance related effects, all over the world. This study aims to evaluate noise pollution in four urban parks located in Sanandaj City, Iran and to zone it in GIS environment. Sound pressure level (SPL) and maximum sound level (Lmax) were measured at 45 points (each point was ...

The EN 1793-5 and 1793-6 standards have been in use for many years as a method measuring the intrinsic characteristics of noise barriers installed along highways railways. They require sound source grid microphones, to be placed near barrier free field conditions, according predetermined distances. In principle, small errors positioning microphone may affect results obtained. An international r...

Information leaks through regular fiber optic communications is possible in the form of eavesdropping on conversations, using standard fiber optic communications as illegal measuring network. The threat of leakage of audio information can create any kind of irregular light emission, as well as regular light beams modulated at acoustic frequencies. For information protection can be used a means ...

In this study, we use numerical methods to study the acoustic streaming effect of black hole (ABH). Firstly, build an ABH model effect. By deriving waves equations and solving Navier–Stokes equations, obtain flow field, sound temperature field under excitation. Secondly, simulation result reveals mechanism effects on transmission characteristics cavity ABH. The results show that abrupt decrease...

Elastomers are finding wider and wider applications throughout industry. For example, the automotive industry is continually attempting to improve fuel efficiency. The resulting reduction in body and engine weights put increasing pressure on suspension and sound insulation designers to meet the car buyers demands for improved ride quality and quiet cars. Designers are no longer satisfied with s...

In this research, we propose and design an acoustic metamuffler (AMM) by coupling a microperforated plate composite waveguide formed main Helmholtz resonator. The proposed mechanism deliberately designed structure are conducive to generating multimode resonances that help improve the absorption effect lead broadband (4 octaves) sound insulation. We develop effective circuit model analytically p...

Wooden foams have been extensively researched in recent years because of their special structure and green features. At the same time, noise pollution is increasing, prompting sound insulation to become another research focus. In this study, a three-factor, five-level orthogonal experiment was designed, 25 sets specimens were produced for testing analysis 19 frequency bands. To measure insulati...