Headphone noise: occupational noise exposure assessment for communication personnel

For communication personnel exposed to noise emitted by headphones, the sound pressure level measured at the position of the exposed person (but the person absent) does not adequately represent the sound exposure. The first section of this paper reports comments concerning the legislation, the relevant international standards and the state-of-the-art of researches in this field. Then, the second section reports the results of an experimental study undertaken in four different occupational settings in order to detect whether a risk of hearing damage exists for the workers exposed to noise emitted by headphones. During the recordings a headphone identical to that worn by the telephone operator has been positioned on a manikin as to reproduce the same auditory condition. In order to assess the noise exposure, the recordings have been post processed by means of different frequency dependent transformations. The analysis of the results have shown that for some workers the risk of hearing loss exists. The implementation of a sound level limiter directly connected to the headphone has shown a good evidence: the output level never exceeds the defined threshold and the attenuator reacts in a very short time, providing a reduction of 10 dB in 0.3 seconds.