Practical Research On Personal Attenuation Rating Of Noise

ObjectiveTo assess the expose of occupational noise and listening health,control noise riskfactors，and reduce the harm for workers, and enact hearing protection for industry, allsurvey were carried for understanding the foundational situation of noise pollution andmanagement in a petroleum machinery manufacturing company, with the occupationalenvironmental noise dose and individual absorbed dose level was measured．true earbuilt-in microphone E-A-R fit authentication system was used for selecting earplugsin protective, comfortable, operable and economic way, personally with in studying onthe spectrum characteristics of earplugs for testing.Methods1.Monitoring occupational environmental noise level： one petroleum machinerymanufacturing company was selected as typical study object， then find out theconstitute of the noise source and equipment condition in order to determining thenature of the characteristics of noise source and noise．The noise measured in line withGBZ/T189.8-2007.According to GBZ/T2.2-2007， measurement is set to A meterpower and the “S” file take the equivalent sound level LAeqin noise monitoring soundlevel meter．2.Measurement and evaluation of individual absorbed dose level：Healthy physicalchart of workers was developed according to GBZ188-2006．Pure tone air conductionaudibility threshold test was carried out．Occupational hearing loss was diagnoseddetermined in line on GBZ49-2014.3.Comparing with the individual PAR and the noise level in normal working throughthe E-A-R fit system, the final synthesis results will be given, then judging theprotective sufficiency for that earplug in this wearing manner for the workers. And themaximal acceptable noise expose level would be figure out by the E-A-R fit systemimmediately.Results1. There were28monitoring data in noise environment， the point which noiseintensity was greater than or equal to85dB(A) were24,the percentage was85.71．Thespectrums of sound pressure level were differences in workshop in different positions,and the differences also exist in high frequency and low frequency. 2. The rate of speech frequency hearing loss and high frequency hearing loss are43.46%and54.49%. There were greater incidence of heating loss， mostly highfrequency damage，the general trend was existed，and hearing loss rate was risingalong with the extension of the Length of service. The incidence and severity ofhearing loss related with working age.3. There are306workers were selected in this test with E-A-R fit system.The acceptable rating of1100、312、318、340model earplug were54.58、44.12、71.90and77.78. Their main noise protection respectively was2000~8000Hz,500~2000Hz,1000~8000Hz and1000~4000Hz.Conclusion1. The exposure of noise level in all workplaces detected, are mainly distributedrang from85to103dB(A), so most workplace are not conformance for workers. Thenoise spectrum distributions in different workplace are not the same, that the exposedperson must select diverse earplug.2..With the accumulation of noise exposure time, the more serious the hearingloss. Workers the of speech frequency and high-frequency loss from the length of lessthan5years group,10~20years group,20~30years group, and higher than30yearsgroup, showed a trend of increasing the30years of change, and the incidence ofhearing loss degree of light, medium and heavy also show the tendency of increasegradually.3.1100and312model can used to protect in high frequency and340modelacting in Intermediate frequency protection.318model， with wider range ofprotection, the earplug can be used to wear in inspection station.