نتایج جستجو برای: noise control
تعداد نتایج: 1505459 فیلتر نتایج به سال:
ارزیابی عملکرد آکوستیکی مانکن سر جهت استفاده در آزمون های تعیین قدرت کاهندگی صدای وسایل حفاظت شنوایی
Introduction:One of the recommended methods for evaluation effectiveness of hearing protection is use the acoustic fixture accordance with standard ISO 4869-3. The aim of this study was evaluate the acoustic performance of fixture for using in noise reduction rate tests of hearing protection devices in the laboratory. Methods: In this cross-sectional study , noise reduction rates o...
we investigated the issue of noise pollution in the bidboland gas refineryby noise measurement and surveys. the bidboland gas refinery has several process units.the sound pressure levels were measured at several places, such as units of 200, 300,400, 500, boiler, powerhouse area, cooling towers pumps, and maintenance area, and thecorresponding noise maps were produced by using sound plan softwa...
noise is defined as unwanted or objectionable sound. human susceptibility to noise varies in terms of intensity, altitude, timbre of sound, personal sensibility, age, and history of ear disorder. noise pollution which is the result of heterogeneous and uncontrolled developments of cities is one the serious problems in large cities of iran. although noise pollution in kerman (located in southeas...
Background and Objectives: Noise-induced hearing loss is a prevalent work-related morbidity in the country. We determined the strength of association between hearing loss and occupational noise exposure as the first step in prevention programs.Material and Methods: A historical cohort study involving 100 exposed and 31 non-exposed subjects was conducted. Noise exposure was estimated using sound...
In this paper, the control of sound propagation in an air-handling duct is investigated. Employing identified discrete t ime models of the duct, robust linear controllers are designed using the combined pole placement/sensitivity function shaping method. T h e particularities of harmonic noise sources are taken into account, avoiding the classical stochastic adaptive and the reference noise bas...
Background & Objectives: Noise is one of the most detrimental factors in working environments that alongside other physical problems have adverse effects on the mental health of employees. Open plan offices such as banks are under the influence of noise pollution sources, which can have a negative impact on health and comfort of employees. This study aimed to identify the sources of noise...
This paper presents the development of a dynamic Active Noise Control (ANC) algorithm aimed towards reducing broadband noise inside helmet earcups fighter aircraft pilot helmet. The ANC involves Variable Step-Size Griffiths (VSSG) FxLMS to attenuate entering directly through helmet, LMS based adaptive canceller microphone, and energy detectors for failure protection optimized battery power usag...
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