Occupational noise exposure for call-center workers

For communication personnel, the occupational noise has to be determined in the ear canal as effect of sound immission from sources placed closed to the ear. This measurement could be carried out directly using miniature or probe microphones, or indirectly using a manikin equipped with ear simulators including microphones. In both cases, special care should be addressed to experimental determination of the frequency-dependent transformation based on the gain exerted by the ear at different frequencies. The investigation dealt with both measuring techniques. It has been undertaken in 74 different work stations (7 call centers) on 83 different types of receivers (supra-aural earphone, insert earphones, telephone handsets) for a 30 hour total monitoring time. Results show that the noise exposure levels are extremely variable: from a minimum value of 50 dB(A) to a maximum value of 87 dB(A). Moreover, the level of 80 dB(A) is exceeded in 23% of cases. By these data we can conclude that the risk of hearing loss could exist for some workers in certain conditions, as previously reported also by other researchers