background: one of the most widely used equipments in harvesting hay and grains are four wheel mowers. the aim of the present study was to determine the levels of noise exposure in drivers and bystanders in different states, speeds and gear of four wheel mowers (bcs model 622).   methods: the iso 5131 and iso 6814 standards were used to assess noise exposure in drivers and bystanders, respectiv...

background : cement industry has many process units. basically all of these units can be considered as a source of noise. since noise pollution is defined based on its offensive hearing effects, the importance of the noise sources depends directly on the number of workers in the unit.   materials and methods : an experimental study has been done at tehran cement factory to recognize and analyze...

background: the basic requirements for monitoring anesthetized patients during surgery are assessing cardiac and respiratory function. esophageal stethoscopes have been developed for this purpose, but these devices may not provide clear heart and lung sound due to existence of various noises in operating rooms. in addition, the stethoscope is not applicable for continues monitoring, and it is u...

Sound measured at various points around the environment can be evaluated by a series of multi-pole sources and their acoustic strength can be acquired. In this numerical study, a method, called the inverse method, was examined to achieve this goal. A variety of arrangements of different sources were considered and the acoustic strength of these sources was acquired. Through the application of t...

Background. A field study conducted by researchers found the balls used by visual impairment students at school basically used the sound by a small bell inside the ball. However, the sound emitted from the ball is very limited, the ball will sound when it is moved. This makes it difficult for students with visual impairments to find a missing ball that not emitted makes a sound. Objectives. A ...