Relation between personal level of noise exposure and noise induced deafness

ABSTRACT

This study was formulated to reveal the dose response and dose effect relationship between personal noise dosimetry and occupational noise induced deafness using 2 methods of deafness assessment. The included 368 production workers were from four factories. The selected workers had a mean age of 33.07 +/- 5.99 years, and exposed to noise for a relatively short period, 5.94 +/- 3.96 years. More than 65% of workers suffered from noise deafness using either method. Including level of hearing at 4000 Hz proved to be very beneficial for assessment of the relation between noise level and degree of occupational functional hearing loss. Type of noise, noise peak level, duration of exposure in addition to level of personal noise level proved to be important factors for predicting occupational hearing loss. Dose response relationship curve showed that increased noise level was accompanied by an increased proportion of workers suffering from noise deafness. At noise levels exceeding 100 dB all exposed workers suffered from occupational deafness. Due to the short duration of exposure most of the workers suffered from mild deafness