Correlations between certain hearing changes and vegetative balance in miners.

This study responds to the priorities of the National Health Strategy aimed at control and mitigation of the hazardous effects of the workplace factors on cardio-vascular diseases of people in active working age from the branch "Mining industry". The aim of this work is to study the vegetative balance (by analysis of heart rate variability--AHRV) and the correlations with the state of miners' hearing functions. Sixty eight miners (diggers and mate-diggers) from mining industry were studied.

Masking effect of music upon oral information processing.

The masking effect of three types of music and white masking noise upon special audiometric tests was determined in laboratory c. The stimulus-noise (S/N) ratio was found to be the most considerable factor influencing oral information processing in spite of the type of music or noise used as a masking agent. All types of music (modern, classic or modern music records in backwards order) showed no significant differences in masking being in the same way stronger maskers as white noise.

The "cost" of silence.

Changes in the organism of control desk operators caused by difficulties faced during productionally relevant speech information processing under conditions of intense occupational noise, represent the psychophysiological "cost" of noise masking. Its presence attests to difficulties in processing before deterioration of the quality of the latter while its quantitative characterisation correlates positively with the degree of the masking effect of noise and with the neuropsychic stress of this particular type of work. For this reason an attempt is made to demonstrate noise masking under laboratory conditions with it approximate quantitative evaluation at two signal/noise ratios- +15 and The statistically significant differences between the values of pulse rate, plethysmography and vocal exertion at the above ratios point to both its presence, and to the necessity to be considered when assessing the occupational burden and standardisation of noise intensity in productions associated with speech signals.

[The evaluation of indices of noise impact on humans].

Due to noise, information processing changes, rate and quality of work deteriorate. Laboratory experiments prove noise exposure to increase dyastolic blood pressure. Multiple factors of occupational environment induce significant individual variability of blood pressure, putting a little value to blood pressure changes.

Changes in some psychophysiological parameters in speech information processing under masking noise effect.

The aim of the present work was to study the influence of masking broad-band (white), impulse and interrupted noise with intensities LAeq 60 and 90 dB(A) on the execution of some psychophysiological tasks. The following parameters were studied: pulse frequency and variation, breathing frequency and variation, vascular tone etc. The psychological tasks model different parts of the operators' activity and include: conduction of mathematical calculations at datum speed; test related to the information processing; complex optional task supplied by Piorkovski's device.

[The hygienic ergonomic protection of speech communication over time].

In the course of the experimental laboratory studies it was found out a significant impairment of the communication following a 2-hour processing of speech signals in conditions of masking noise. In order to diminish the auditory exhaustion in impeded communication the authors created physiologically grounded model of the working and resting regime in accordance to the experimental data, which require the including of two breaks in the first half of the working day, i.e.

[A method of rapid evaluation of conditions of verbal communication in noisy industrial surroundings].

The article deals with creation of an express method using nomograms to evaluate conditions of verbal communication in noisy industrial compartments. Experimental creation of the nomogram requires alternate impulsive and constant noise. The method enables to forecast results of verbal understanding in noisy industrial conditions.

[The effect of different types of music on the perception of speech information].

Under experimental conditions, the masking effect of three types of music and of "white" masking noise was studied using a special speech-audiometric test (L. Tsaneva 1978, 1993). The signal-to-noise relation was found to be the most significant factor affecting spoken information perception, regardless of the type of music used as masking agent (level of correlation coefficients, jR = 0.

[The effect of different masking noises on psychophysiological tasks].

This paper describes experimental investigations aimed at clarifying the influence of wide-range (white), pulsed and interrupted noise with intensities Lequ 60 and 90 dB (A) on some psychophysiologic characteristics of problem solving. Physiologic indicators were recorded: pulse rate and variance, breathing rate and variance, vascular tone, ets. Psychologic problems to be solved modeled various features of operator activities, including: performing mathematical computations at a given rate; a test involving information processing; a compound option problem offered by Piotkovski's apparatus.

[The mapping of the masking effect of noise in relation to the adaptive potentials of the auditory analyzer for speech communication].

The work considers the problem of ergonomic evaluation on the abilities of the auditory analyzer for speech information processing, depending on the zones of masking effect of noise and the rate of speech communication. Significant increase the loss of speech communication with increase in the intensity of the masking effect of noise (from 21.33% at L eq.

[The discomfort threshold studied in operators at the control consoles in automated production with a view to its use in job selection].

The results from the investigation of the threshold of discomfort in 385 operators from firm "Kremikovtsi" are discussed. The most expressed changes are found in operators with increased tonal auditory threshold up to 45 and above 50 dB, in high confidential probability. The observed changes in the threshold of discomfort are classified into 3 groups: 1).

[Changes in the functional state of the visual analyzer in operators working with video display terminals].

Research in laboratory and on-site conditions was performed to establish correlations between the visual analyzer's functional shifts in display operators, and the duration of work, the type of the screen used (coloured or non-coloured), the duration of the eyes, fixation on the screen, as well as sex related differences.