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2 Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje

2 2001

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The influence of vibration on the hearing organ and the vestibule

100%

Pośpiech L.

tom Vol. 83, nr 27

37-37

Vibrations are transmitted to the systemic organs during immediate contact with a vibrating ground e.g. in transport workers or a vibrating tool, as in jackhammer operators. Long-lasting, most commonly occupational exposure to vibration is a frequent cause of a syndrome referred to as vibration disease. The disease has been included into the occupational diseases register. Three forms of vibration disease may be distinguished, associated mainly with local effects of mechanical vibrations: vasoneurotic, bony and mixed. The harmful effect of mechanical vibrations depends on the degree of load, i.e. exposure time, the manner of contact of the body with the vibrating element as well as on physical parameters, i.e. frequency and amplitude. Most harmful are vibrations which are in the range of resonance frequencies of individual organs. The values for the head are 4-5 Hz and 18 - 25 Hz Experimental studies on animals have demonstrated the incidence of degenerative changes in all the turnings of the cochlea, most evident in the upper turning and decrease of the value of microphonic potentials in the low and medium frequency range under the influence of low frequency vibrations. Degenerative changes and mechanical injuries of the otolith organ, the cupula and vestibular nuclei were also found in animals exposed to whole body mechanical vibrations with the frequency of 10-25 Hz. Low frequency vibrations result in rotary movements of the head which lead to angular acceleration and irritation of the nerve endings in the labyrinth. Since all the vibrating facilities also produce noise, the clinical studies involve simultaneous effect of vibration and noise on the hearing and balance organs. Own examinations of water-borne transport workers exposed to whole body vibrations and noise revealed deterioration of hearing acuity in the range from 500 to 4000 Hz as well as damage to the peripheral part of the vestibular organ in 48% of the subjects. Parallel incidence of hearing and balance impairment was not demonstrated in the same subjects. The lesions were found to be associated with duration of employment. The disturbances were found to be more advanced in workers employed in 24-hour system than in those working in 12-hour system.

Wstępne badania doświadczalne wpływu promieniowania mikrofalowego na elektrofizjologię ślimaka świnki morskiej

51%

Michalski W. , Preś K. , Pośpiech L.

tom Vol. 83, nr 27

341-346

It is well known that mechanical trauma, excess noise level, vibrations, some kinds of antibiotics can cause hearing injuries of different intensity. Lack of informations on influence of electromagnetic radiation on the organ of hearing. An experiment with microwave radiation (MR) of 10,5 GHz frequency has been described in the paper. Twenty coloured guinea pigs were used in the experiment. Measure of electric activity of cochlea was level of cochlear microphonic (CM) induced by sinusoidal acoustic wave of the known frequency and intensity (in dB). The induced CM signals were measured prior to and after microwave irradiation in the same experimental condition. Thanks that the MR was the only factor which could change electric cochlea activity. Three animals were irradiated by 1 hour at power density of 0,3 mW/cm2. Decrease of the CM values was observed. Seventeeth animals were irradiated by 0,5 hour at power density 0,5 - 1 mW/cm2. In 13 causes essential drops of CM levels was observed. Further experiments will be follow this preliminary one.