Continuous or intermittent noise exposure, does it cause vestibular damage? An experimental study.

OBJECTIVE

Aim of this study was to compare vestibular changes in guinea pigs exposed to same level of continuous and intermittent noise by electron microscopy.

METHODS

The study included 10 adult albino guinea pigs. In a silent room, a 4-kHz octave band noise at an intensity of 120 dB SPL was presented. Six animals were exposed to continuous noise for 6h, and four animals were exposed to 12h intermittent noise. One day after noise exposure eight guinea pigs were decapitated and temporal bones of one side were removed. Ten days after continuous noise exposure two guinea pigs were decapitated. They were examined with an electron microscope.

RESULTS

The most characteristic changes in the macula of the continuous noise exposure group were degeneration of the epithelial cells and separation in their layers. Marked crystolysis and stromal cell apoptosis were also noted in this group compared to the intermittent noise exposure group. Effect of noise was more obvious in the group that continuous noise was applied. The histological changes in group which examined after 10 days were similar to the group that examined after 1 day.

CONCLUSION

Continuous noise can cause more damage to the vestibular system compared with intermittent noise and histological changes after continuous noise are permanent.