The recovery of vascular changes following brief noise exposure.

Histological measures of cochlear vasculature and blood flow were examined in 20 guinea pigs. Sixteen were exposed to octave band noise at 120 dB SPL for 30 min and then permitted to survive after the exposure for 6 h, 18 h, 48 h, or 4 weeks (N = 4 in each group). Control animals were exposed to the laboratory and apparatus but not to the noise and then sacrificed after 48 h (N = 2) or 4 weeks (N = 2). Statistically significant results indicate that the noise exposure resulted in reduced RBCs in the cochlea for animals permitted to survive 6 to 18 h after the noise exposure. These changes, however, were no longer apparent in animals which were permitted to survive 48 h or 4 weeks after the noise exposure. The vascular sequelae of 30 min exposure to 120 dB octave band noise appear to recover within a few days of the exposure.