THE COMPARISON OF THE NOISE REDUCTION LEVEL IN THE EARS WHEN USING EARMUFFS DURING METAL STAMPING WORKING AMONG AUTO PARTS MANUFACTURING WORKERS WITH CALCULATION VALUE USING NIOSH’S RECOMMENDATION METHOD

Abstract

          The NRR specified by manufacturers on the label of devices should be considered for selecting a hearing protection device to reduce Effective A-weighted sound pressure level: (L’AX) .The purposes of this study were aimed to compare to measure the noise level inside the ears while wearing hearing protection devices with the calculation (L’AX) of by using NIOSH’s recommendation formula. This study is cross sectional study. Study in an Automotive Parts Manufacturing Company. The data of this study were collected by measuring the noise levels inside the ears of workers while they were wearing an ear muffs, by using a sound level meter. The test process utilizes two sound level meters with microphones positioned with one inside the ears while wearing an ear muffs and the other outside the subjects’ ears. The sound level measured inside the ears are ENLs obtained from measurements and the calculated ENLs were obtained from calculation of noise levels outside the ears and the NRR. The results show that measured ENLs were significantly less than the calculated ENLs using NIOSH’s recommendation formula (P<0.001). The average measured attenuation of the muffs were 16.57, 19.68, 20.21 and 22.45 dBA respectively. This was better than that of the calculated NRR, using NIOSH’s recommendation formula, which was 8.75, 11.75, 13.25 and 15.5 dBA respectively.