The aim of this study is to determine the actual efficiency of the present medical treatments of acoustic trauma. Untreated and treated groups of guinea pigs are exposed to a traumatic noise exposure, inducing up to 60-dB threshold shift. The recovery is followed for up to 14 days. The first results indicate that in some animals the recovery of the threshold shifts are complete despite the fact that significant areas of hair cells are damaged. The most widely used medical treatments of acoustic trauma (oxygenotherapy, carbogen, hyperbaric oxygen, vasoactive agents, and corticotherapy) have been tested. Preliminary results indicate that pure oxygen and carbogen seem ineffective, hyperbaric oxygen used alone is dangerous, and corticoids and combined corticoid/hyperbaric oxygen seem to improve functional and morphological recovery. This study will be taken as a reference to look for new treatments that will be applied directly to the cochlea by means of an implanted osmotic micropump.

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There have been reports that the developing ear is more sensitive than the adult ear to noise-induced hearing loss. This was investigated by testing auditory function in rats, both electrophysiologically and histologically, following exposure to broad-band noise (12 h/day for 15 days) at different stages of auditory development (neonates and adults), and also in age-matched controls. An exposure of 90 dB SPL broad-band noise caused no long-term change in auditory function in either age group. A higher exposure (102 dB SPL) caused greater long-term changes in hearing in the adult compared to the young noise-exposed rats, although histology showed greater damage to hair cells in the younger animals. Therefore, functionally, the developing ear does not seem more vulnerable than the developed ear to acoustic trauma.

No abstract