[Combined effects of noise and vibration on the cells of the hearing and vestibular organs].

Guinea pigs were used to study the combined effect of total-body vibration (with the peak values in the mean geometric frequency of 31.5 and 63 Hz octave bands equal to 66 and 76 dB, respectively) and constant wide-band noise with the sound pressure 85 dBA, 90 dBLin. The exposure time was 3 hrs as well as 1, 5, 10, 15, 20, 60 and 90 days of 3 hrs daily. The combined action of noise and vibration with the above characteristics produced a deleterious effect on receptor cells of the hearing organ, particularly of the spiral organ. The changes were recorded in the form of rhythmical functional pulsation of nuclei. As the exposure continued, these changes increased, involving almost every sensitive cell of the spiral organ. It was concluded that within the first 20 days the changes were reversible. During more extended exposure (60 and 90 days) the changes in hair cells of the spiral organ, which included nuclear deformation and disintegration of chromatin, mitochondria and endoplasmic reticulum membranes, became irreversible and caused the decay of injured cells.