Summary Background The biological effects of noise depend on its physical parameters, combination with other hazards, the content of acoustic signals. This article aimed to analyze the difference in biological effects caused by the selection of nonverbal and verbal signals in conditions of a high level of work intensity. Methods Work conditions, physical characteristics of noise, levels of work intensity were studied among 75 telephone operators and 96 geophone operators. Levels of permanent hearing thresholds, evaluated by pure-tone audiometry, and results of self-estimation of operators’ health were compared. The contribution of the content of acoustic signals in the shifting of hearing thresholds was evaluated by the one-way analysis of variance. Results Selection of acoustic signals in the noise background (< 65 dB), in conditions of high work intensity, causes a significant increase of permanent hearing thresholds in both studied groups comparing to the non-noise exposed population. A combination of the high level of work intensity and distinguishing of nonverbal acoustic messages leads to significant deterioration of health resulting in decreasing of hearing sensitivity and a number of complaints on the state of health (p < 0.05). The content of acoustic signals significantly contributes to the biological effects of the nose. Conclusion Obtained results testify necessity to revise safe criteria of noise levels for workers, engaged in selection, recognition and distinguishing of acoustic messages in the noise background combined with a high level of work intensity. In case when the energy of the acoustic field cannot be reduced, occupational safety measures should focus on decreasing of work intensity.

This paper reports a study into the quantitative values and dynamics of physical factors in premises and workplaces of stationary and portable computers. The factors that are practically not perceived by the senses of operators were investigated. It is established that modern monitors do not generate electromagnetic fields of hygienically significant levels. System units generate electric fields (18‒22 V/m) and magnetic fields (220‒245 nT) that are approaching the maximum permissible. Sources of uninterruptible power supply and fluorescent lighting systems generate excess magnetic fields (up to 2250 nT and 2300 nT), respectively. The main excessive factor for portable computers is electric fields (up to 9 kV/m), which is the cause of air deionization in the user's zone of stay. It is shown that one system unit in the normative volume of the room (20 m3) deionizes air (into 100 cm-3 positive and 200 cm-3 negative). The generation of ions by modernized laser printers and photocopiers of various models (up to 1500 cm-3 and 2800 cm-3, respectively) was investigated. The distances at which the ionic composition of the air corresponds to the background values (1.0‒1.5 m) were determined. That requires the introduction of artificial air ionization in workplaces of users and a decrease in the levels of electrostatic fields. The spectral composition and amplitudes of magnetic fields of external power supplies of laptop computers were determined. It is shown that the difference in sound levels measured on the scales "Lin" and "A" reaches 24 dB, which indicates a significant impact of infrasound on users. Membrane-type protective panels configured for maximum resonant frequencies of low-frequency sound and infrasound have been proposed

Much attention is paid to the development and study of protective properties of materials for shielding electromag-netic fields. This can be explained by the growth of electromagnetic load on the production equipment and personnel and environment [1]. In particular, there is a tendency towards higher amplitudes and a broader frequency spectrum

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Aims:The functional state of the auditory analyzer of several operators groups was study. The objective of this study was to determine some characteristics of hearing impairment in relation with features of acoustic stimuli and informative significance of noise.Materials and Methods:236 employees (middle age 35.4 ± 0.74 years) were divided into four groups according to features of noise perception at the workplaces. The levels of permanent shifts of acoustic thresholds were estimated using audiometric method.Statistical Analysis Used:Common statistical methods were used in research. Mean quantity and mean absolute errors were calculated. Statistical significance between operators' groups was calculated with 0.05 confidential intervals.Results:The peculiarities of hearing impairment in observed groups were different. Operators differentiating acoustic signals had peak of hearing impairment in the field of language frequencies, while the employees who work with noise background at the workplaces had maximal hearing threshold on the 4000 Hz frequency (P ≤ 0.05).Conclusions:Hearing impairment depends both on energy and human interaction with acoustic irritant. The distinctions in hearing impairment may be related with the necessity of recognizing of acoustic signals and their frequency characteristics.