Search results for "Internal noise"
showing 2 items of 2 documents
Noise Levels in an Urban Hospital and Workers' Subjective Responses
1995
Internal noise levels were measured in a 232-point grid that encompassed the main building of a major University Hospital in Valencia, Spain. Most noise equivalent sound levels that were obtained exceeded 55 dBA, and in some instances these sound levels were very high. Hospital workers' subjective responses to noise were evaluated with a self-answered questionnaire. A total of 295 workers volunteered to participate. Their answers revealed that the most important noise sources were located primarily inside the hospital. Noise levels were perceived to be sufficiently high to interfere with their work, and noise levels were also thought to affect patients' comfort and recovery. Most subjects t…
Study and Simulation of Helicopter Gearboxes Noise
2010
International audience; Main gearbox is one of the main noise sources in helicopter cabin. In order to improve the comfort of customers and reduce the health impact, acoustic and vibration mechanisms of gearboxes have to be understood and simulated during development phases. Thus, we first present the global methodology chosen to compute main gearboxes noise in helicopter cabins. Secondly, we described the way we compute mechanical excitation sources induced from gear mesh, static transmission error and meshing stiffness. Depending on the type of gear, we compute those using either analytical specially developed code or EC codes. Thirdly, we propose a modeling to compute dynamic loads on be…