Cochlear neuropathy in the rat exposed for a long period to moderate-intensity noises.

Damaging effects on the cochlea of high-intensity acoustic overexposures have been extensively documented, but only few works have focused on the danger of moderate noise levels. Using scanning and transmission electron microscopy, we explored the noise-induced neuroepithelial changes that occur in the cochlea of rats subjected to moderate intensities, 70 and 85 dB SPL, for an extended period of time (6 hr/day over 3 months). Although the full quota of outer and inner sensory hair cells remained present, we detected discrete abnormalities, likely resulting from metabolic impairment, in both types of hair cell within the basal region of the cochlea.

Morphological changes of adrenal gland and heart tissue after varying duration of noise exposure in adult rat.

Noise was considered an environmental stressor causing a wide range of health effects such as acoustic, cardiovascular, nervous, and endocrine systems. The present study was performed to examine the effects of a repeated noise exposure on adrenal gland and heart tissue. The results showed that exposure to moderate intensity sound (70 dB[A]) causes time-dependent changes in the morphological structure of the adrenal cortex that involve disarrangement of cells and modification in thickness of the different layers of the adrenal gland.

Qualitative and quantitative assessment of noise at moderate intensities on extra-auditory system in adult rats.

Noise has long been realized as an environmental stress causing physiological, psychological and behavioral changes in humans. The aim of the present study was to determinate the effect of chronic noise at moderate intensities on both glandular and cardiac function and oxidative status. Our problem comes from working conditions in call centers where operators are responsible for making simple and repetitive tasks.