The effect of noise on ears with a hole in the vestibule.

CONCLUSION

A hole in the vestibule of the inner ear leads to augmentation of the hearing loss following noise exposure. Further research is needed to ascertain the mechanism.

OBJECTIVES

The possible effects of a hole in the wall of the inner ear at the vestibule on noise-induced hearing loss were assessed.

METHODS

The study was conducted on a total of 14 sand rats. Of these 14 animals, 10 underwent baseline auditory nerve and brainstem evoked response (ABR) threshold measurements in each ear separately (insert earphone), opening of middle ear bulla in both ears and drilling of a hole in the vestibule of one inner ear. The other ear was sham-operated. Following immediate re-assessment of ABR threshold, the 10 animals were exposed to 113 dB SPL broadband noise during 4 nights, and 3 days later ABR measurements were repeated. Four additional animals with a hole in one vestibule, not exposed to noise, served as controls.

RESULTS

Following noise exposure, ABR thresholds were elevated by 28.5 +/- 9.1 dB in the ears with the hole, and by 15.5 +/- 7.2 dB in the opposite ear without the hole (significant difference, p < 0.003). In the four control ears, ABR threshold was not elevated a week after drilling the hole.